Syrian warplanes and artillery have pounded the central city of Homs, subjecting the former rebel stronghold to its worst bombardment in months.
The Britain-based Syrian Observatory for Human Rights said Friday's attack was the worst the city had seen in five months. The Observatory, which relies on a network of activists on the ground, said tanks and mortars as well as aircraft had bombarded the city's Khaldiya neighbourhood.
"Around dawn, the regime went crazy and started shelling hysterically," a Homs-based activist known as Abu Rami told the Associated Press news agency via Skype on Friday.
"An average of five rockets a minute are falling." Abu Rami was speaking from the central opposition-held old quarter known as Old Homs. He asked to be identified by his nickname for fear of regime reprisal.
He said the government forces were mainly firing rockets and heavy mortars at the rebel-held neighbourhoods of Old Homs, Khaldiya, Qusour and Jouret el-Shayah.
Abu Rami also said the regime forces had been shelling villages around Homs and the rebel-held town of Rastan, just north of the city.
There were no immediate reports of casualties.
Activists say most government forces near Homs are stationed outside the town - a common pattern in rebel strongholds.
The Observatory also said Syrian military had been shelling the neighbourhood of Sakhour in Aleppo as government forces battle rebels in the country's largest city.
State-run Syrian TV said that government forces "cleansed Sakhour of terrorists and mercenaries".
The latest offensives came as the United Nations Security Council unanimously approved a statement condemning "in the strongest terms" Syria's shelling of a Turkish town that killed five people.
Council members managed to bridge differences between the strong statement demanded by the United States and its Western supporters and backed by their NATO ally Turkey, and a weaker text pushed by Russia, Syria's most important ally, after negotiations that began late on Wednesday and continued until Thursday.
In the press statement, which needed approval from all 15 council members, the UN's most powerful body said the incident "highlighted the grave impact the crisis in Syria has on the security of its neighbours and on regional peace and stability."
It also extended condolences to the families of the victims and to the government and people of Turkey.
The council demanded an immediate end to such violations of international law and called on the Syrian government ``to fully respect the sovereignty and territorial integrity of its neighbours.'' Russia's agreement that the Syrian shelling violated international law was a key concession by Moscow.
'Terrorists and insurgents'
The original Western-backed draft, proposed by Azerbaijan, condemned the shelling "in the strongest terms" and called it a violation of international law. Proposed Russian amendments never mentioned any breaches of international law, so the inclusion in the final text was a concession by Moscow.
Earlier on Thursday, Syria's UN envoy said his government was not seeking any escalation of violence with Turkey and wanted to maintain good neighbourly relations.
Ambassador Bashar Ja'afari said the government did not apologise for the shelling from Syria because it was waiting for the outcome of an investigation on the source of the firing.
He read reporters a letter he delivered to the Security Council that sent Syria's "deepest condolences" to the families of the victims "and to the friendly and brotherly people of Turkey."
In-depth coverage of escalating violence across Syria
It urged Turkey and its other neighbours to "act wisely, rationally and responsibly" and to prevent cross-border infiltration of "terrorists and insurgents" and the smuggling of arms.
The border violence has added a dangerous new dimension to Syria's civil war, dragging Syria's neighbours deeper into a conflict that activists say has already killed 30,000 people since an uprising against President Bashar al-Assad's regime began in March 2011.