Syrian troops have continued shelling residential neighbourhoods in the central city of Homs for the fifth straight day, killing scores of people, activists said.
The British-based Syrian Observatory for Human Rights said "tens of citizens were killed" in the shelling of the neighbourhoods of Bayadah, Baba Amr, Khaldiyeh and Karm el-Zeytoun.
Omar Shaker, an activist in Baba Amr, said his neighbourhood had come under "very intense shelling" by tanks, mortars, artillery and heavy machine guns.
Mr Shaker said he had counted five bodies today in his district.
The violence comes as President Bashar Assad's regime is increasingly isolated.
Five European and six Gulf nations have pulled their ambassadors out of Damascus, and the US has closed its embassy in Syria.
Activists say the assault on Homs is the Syrian regime's final push to retake areas controlled by the rebels.
The violence comes as President Bashar Assad's regime is becoming increasingly isolated over its bloody crackdown on dissent.
But Assad was bolstered yesterday by a visit from Russia's foreign minister Sergey Lavrov and the country's intelligence chief, Mikhail Fradkov. In talks in Damascus, the Russians pushed for a solution to the Syrian crisis that would include reforms by the regime and dialogue with the opposition - but not for Assad to step down.
During the meeting, Assad said Syria was determined to hold a national dialogue with the opposition and independent figures, saying his government was "ready to co-operate with any effort that boosts stability in Syria", according to the state news agency SANA.
The Syrian opposition rejects any talks with the regime and say they accept nothing less than Assad's departure.
On Saturday, Russia and China blocked a Western and Arab-backed UN Security Council resolution supporting calls for Assad to hand over some powers as a way to defuse the 11-month-old crisis.
The Syrian Observatory for Human Rights said at least 50 people were killed in today's shelling of the Homs neighbourhoods of Bayadah, Baba Amr, Khaldiyeh and Karm el-Zeytoun. The group also said that 23 homes were heavily damaged in Baba Amr alone.
"The situation is dire. We are short of food, water and medical aid. Doctors have collapsed after treating the wounded without rest for five days," Mr Shaker said. "We want Lavrov to come and spend a night in Homs to see what we have been passing through."
The activist urged the international community to set up a safe passage so that women and children can leave volatile areas of Homs. The head of the Observatory, Rami Abdul-Rahman, said the regime was trying to "exhaust rebels in preparation for storming neighbourhoods".
The Observatory and another activist group, the Local Co-ordination Committees, also reported intense clashes between troops loyal to Assad and defectors in the province of Idlib, bordering Turkey. The Observatory said at least five soldiers were killed in the clashes.
The UN estimates the government crackdown has killed more than 5,400 people since March, making Syria's conflict one of the deadliest of the Arab Spring.
Hundreds more are believed to have died since the UN released that figure in January, but the chaos in the country has made it impossible for the world body to update its figures.
Mr Lavrov said later that Assad wants his vice president to hold talks with the opposition forces.
After talks yesterday in Damascus, the Russian minister said Assad "delegated the responsibility of holding such a dialogue to vice president (Farouk) al-Sharaa."
Mr Lavrov blamed both Assad's regime and opposition forces for instigating the violence.
He told journalists in Moscow: "On both sides there are people that aim at an armed confrontation, not a dialogue."