Syrian troops advanced on Monday into the rebel-held Khaldiyeh district of central Homs, with shelling intensifying as forces battled for a 10th day in the area, activists and an NGO said.
State media meanwhile reported two car bombs hit a regime-held area in the city.
"The ruthless campaign against Homs is continuing for the 10th day in a row. Regime forces have been able to enter parts of Khaldiyeh after heavy shelling and scorched-earth tactics," activist Abu Bilal al-Homsi told AFP via Skype.
"The situation is similar to Qusayr," he said, referring to another town in Homs province, which was recaptured by army forces after a fierce campaign on June 5.
The activist said the army's assault was the fiercest in Homs city since the beginning of the uprising against President Bashar al-Assad in March 2011.
He said the army was using "every kind of deadly weapon, from planes and rocket launchers to artillery, mortars and tanks".
He said the army controlled around 30 percent of the district, which is north of central Homs, but the Al-Watan newspaper, citing military sources, said troops now controlled "most of Khaldiyeh".
"The Syrian Arab army brought most of the Khaldiyeh neighbourhood of Homs under its control," reported the daily, which is close to the Syrian government.
Both activists and the army said that regime forces had gained control of areas around the Khalid Bin Walid mosque in southern Khaldiyeh.
Videos filmed by activists showed massive destruction in area around the mosque, and the sound of heavy shelling, with blasts ringing out uninterrupted for minutes at a time.
Footages showed shells landing by the mosque's silver domes, sending up shocks of orange sparks and then billowing white smoke.
The Syrian Observatory for Human Rights meanwhile reported "violent clashes between rebel fighters and regime troops and gunmen on the outskirts of Khaldiyeh".
The group, which relies on a network of activists, lawyers and doctors on the ground, said there were reports of casualties on both sides, but gave no further details.
Abu Bilal said some 800 families were trapped in several besieged Homs districts, including Khaldiyeh.
The United Nations has estimated some 2,500 people are trapped amid the fighting that began 10 days ago.
State media meanwhile reported two car bombings in the regime-controlled Akrameh district of Homs city.
The Observatory also reported the attack, but only mentioned one car bomb.
"Two car bombs hit Al-Hadara street in Akrameh district. Several people were killed, according to initial reports," state television said.
The Observatory said Akrameh is home to a majority Alawite population, who come from the same religious community as Assad.
The group said several people were injured but reported no dead, and added that two shells hit the neighbourhood at the same time as the car bomb explosion.
The Observatory said at least 95 people were killed throughout Syria on Sunday, including 24 civilians, 43 rebels and 28 soldiers.