Syrian forces pounded opposition hubs in the cities of Aleppo and Homs on Friday, according to news agency and Al Arabiya reports, adding that regime forces battled fighters around Damascus.
On the ground, violence was also reported in other towns and villages across the country, with the bloodletting showing no signs of any let-up a day after the United Nations formally called time on its observer mission.
At least 157 people were killed across Syria by security force gunfire so far on Friday, according to the Local Coordination Committees activist group.
The army clashed with rebels near the main military airport in Damascus and shelled southern parts of the capital as well as areas of the commercial city of Aleppo and the eastern province of Deir Ezzor, the Syrian Observatory for Human Rights said.
Deadly violence was also reported in the provinces of Homs, including the western village of Houla, and Deraa, the cradle of the uprising that began with peaceful protests in March 2011 but has escalated into an increasingly vicious battle between armed rebels and government forces.
Opposition factions reported that 65 bodies had been found dumped on a rubbish tip in a town near Damascus, claiming the victims had been bound, executed and set on fire by pro-government forces.
It is impossible to independently verify such claims as journalists are unable to report freely in Syria.
With the international community still deeply divided over how to end the conflict, the U.N. said the number of Syrians seeking refuge in neighboring countries had now soared to at least 170,000.
“There has been a further sharp rise in the number of Syrians fleeing to Turkey,” the UN refugee agency said.
Meanwhile, humanitarian conditions in Syria have deteriorated as fighting worsens, cutting off civilians from food supplies, health care and other assistance, U.N. agencies say. Sewage-contaminated water has led to a diarrhea outbreak in the countryside around Damascus, with 103 suspected cases.
Some 1.2 million people are uprooted in Syria, many staying in schools or other public buildings, U.N. officials say. U.N. humanitarian chief Valerie Amos, ending a visit to Syria, said on Thursday up to 2.5 million people needed aid there.