BBC
Security officials in Damascus said the besieged district of Baba Amr would be "cleaned" within the next few hours.
Residents of Homs have long said they believe a ground assault is imminent, but the scale of the operation remains unclear.
It comes amid reports of a new draft UN resolution on the crisis.
The draft, which is still in its early stages, focuses on humanitarian aid for Syria, in the hope both China and Russia, which have opposed previous votes, will back it.
Although diplomats said the move was in the early stage, China said it supported "creating conditions" for humanitarian aid to be sent.
A UN meeting on Tuesday was told more than 7,500 had died in the 11 months of protest against Syrian President Bashar al-Assad.
'Fierce confrontations'
Fresh shelling was reported in Homs on Wednesday morning, a day after more than 100 people were killed, rights groups said. Power to many areas of the city is said to have been cut.
The Associated Press also quoted an official as saying the district would be "cleaned" within hours.
One activist in the city, Mohammad al-Homsi, told Reuters that infantry was moving towards the al-Bassel football stadium just north Baba Amr, and that "fierce confrontations with automatic rifles and heavy machine-guns are taking place there".
The BBC's Jim Muir, reporting from Beirut, says communications with Homs appear to have been cut.
Some activists had told the BBC on Tuesday night that government forces were only about 1km from the press centre which was shelled on 22 February and that they expected to be attacked within hours.
But our correspondent says it remains to be seen whether the latest manoeuvres are the big push into Homs that has been expected.
Two foreign journalists were killed in that blast and three other journalists caught up in it - Edith Bouvier, William Daniels and Javier Espinosa - are still believed to be trapped there.
Sunday Times photographer Paul Conroy was smuggled out to Lebanon on Tuesday in an operation that left 13 Syrian opposition activists dead.
Aid push
The new draft UN Security Council resolution, being drawn up by the US and France, seeks access for humanitarian aid workers and an end to violence.
One diplomat told Reuters the draft had been circulated among "a small circle of like-minded countries".
Another diplomat told AFP: "This resolution will concentrate on humanitarian access to the cities, but it will indicate that the government is the cause of the crisis."
The aim is to make it hard for Russia and China, who are opposed to what they say is forced regime change, to use their veto.
On 4 February China and Russia blocked a UN resolution backing an Arab plan condemning the crackdown and calling on Mr Assad to step down.
China's Foreign Minister Yang Jiechi indicated his country was in favour of creating the conditions for aid to be sent.
Speaking to the head of the Arab League, Nabil Elaraby, over the phone, Mr Yang said China was willing to work with the Arab nations for ''a peaceful and proper settlement of the Syria issue'', the official Xinhua news agency reported.
"The international community should create favourable conditions in this regard and provide humanitarian aid to Syria," Xinhua quoted him as saying.
China's has accused the West of pursuing "hegemonistic ambitions" in Syria under the guise of "humanitarian concern", and correspondents say it remains far from clear whether Beijing will or will not veto any new Security Council resolution.
The Syrian government says at least 1,345 members of the security forces have been killed combating what it calls "armed gangs and terrorists", and puts the number of civilians killed at 2,493.
The Syrian army is advancing on opposition positions in Homs, which has been under artillery bombardment for nearly a month, reports say.
Residents of Homs have long said they believe a ground assault is imminent, but the scale of the operation remains unclear.
It comes amid reports of a new draft UN resolution on the crisis.
The draft, which is still in its early stages, focuses on humanitarian aid for Syria, in the hope both China and Russia, which have opposed previous votes, will back it.
Although diplomats said the move was in the early stage, China said it supported "creating conditions" for humanitarian aid to be sent.
A UN meeting on Tuesday was told more than 7,500 had died in the 11 months of protest against Syrian President Bashar al-Assad.
'Fierce confrontations'
Fresh shelling was reported in Homs on Wednesday morning, a day after more than 100 people were killed, rights groups said. Power to many areas of the city is said to have been cut.
Continue reading the main story 
Edith Bouvier
Thirty-one-year-old reporter for French daily Le Figaro and Radio France Internationale. Sustained a broken femur in the attack which killed US war correspondent Marie Colvin and French photographer Remi Ochlik.
William Daniels
The 34-year-old Paris-based photographer specialises in documenting humanitarian crises. He is represented by the London-based Panos agency and is working with Ms Bouvier on an assignment for Le Figaro.
Javier Espinosa
Spanish daily El Mundo's Middle East correspondent. He began working for the paper in 1994, covering the Rwandan genocide. Has also reported from Mexico and Morocco for the paper. In 1999, he was kidnapped and held for 48 hours by rebels in Sierra Leone.
Trapped Journalists
Thirty-one-year-old reporter for French daily Le Figaro and Radio France Internationale. Sustained a broken femur in the attack which killed US war correspondent Marie Colvin and French photographer Remi Ochlik.
William Daniels
The 34-year-old Paris-based photographer specialises in documenting humanitarian crises. He is represented by the London-based Panos agency and is working with Ms Bouvier on an assignment for Le Figaro.
Javier Espinosa
Spanish daily El Mundo's Middle East correspondent. He began working for the paper in 1994, covering the Rwandan genocide. Has also reported from Mexico and Morocco for the paper. In 1999, he was kidnapped and held for 48 hours by rebels in Sierra Leone.
An unnamed security official told AFP news agency that Baba Amr was now "under control".
"The army has started combing the area building by building and house by house. Now the troops are searching every basement and tunnel for arms and terrorists," he said.The Associated Press also quoted an official as saying the district would be "cleaned" within hours.
One activist in the city, Mohammad al-Homsi, told Reuters that infantry was moving towards the al-Bassel football stadium just north Baba Amr, and that "fierce confrontations with automatic rifles and heavy machine-guns are taking place there".
The BBC's Jim Muir, reporting from Beirut, says communications with Homs appear to have been cut.
Some activists had told the BBC on Tuesday night that government forces were only about 1km from the press centre which was shelled on 22 February and that they expected to be attacked within hours.
But our correspondent says it remains to be seen whether the latest manoeuvres are the big push into Homs that has been expected.
Two foreign journalists were killed in that blast and three other journalists caught up in it - Edith Bouvier, William Daniels and Javier Espinosa - are still believed to be trapped there.
Sunday Times photographer Paul Conroy was smuggled out to Lebanon on Tuesday in an operation that left 13 Syrian opposition activists dead.
Aid push
The new draft UN Security Council resolution, being drawn up by the US and France, seeks access for humanitarian aid workers and an end to violence.
The humanitarian situation in Homs is believed to be deteriorating
Another diplomat told AFP: "This resolution will concentrate on humanitarian access to the cities, but it will indicate that the government is the cause of the crisis."
The aim is to make it hard for Russia and China, who are opposed to what they say is forced regime change, to use their veto.
On 4 February China and Russia blocked a UN resolution backing an Arab plan condemning the crackdown and calling on Mr Assad to step down.
China's Foreign Minister Yang Jiechi indicated his country was in favour of creating the conditions for aid to be sent.
Speaking to the head of the Arab League, Nabil Elaraby, over the phone, Mr Yang said China was willing to work with the Arab nations for ''a peaceful and proper settlement of the Syria issue'', the official Xinhua news agency reported.
"The international community should create favourable conditions in this regard and provide humanitarian aid to Syria," Xinhua quoted him as saying.
China's has accused the West of pursuing "hegemonistic ambitions" in Syria under the guise of "humanitarian concern", and correspondents say it remains far from clear whether Beijing will or will not veto any new Security Council resolution.
The Syrian government says at least 1,345 members of the security forces have been killed combating what it calls "armed gangs and terrorists", and puts the number of civilians killed at 2,493.
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