Syrian forces fired mortars and rockets that killed scores of people in the rebellious city of Homs, activists said, the latest strike in a week-long assault as President Bashar Assad's regime tries to crush increasingly militarized pockets of dissent.
During lulls in the onslaught, Syrians used loudspeakers to call for blood donations and medical supplies.
"There is medicine in the pharmacies, but getting it to the field clinics is very difficult, they can't get the medicine to the wounded," Mohammed Saleh, a Syria-based activist, told The Associated Press by telephone.
As the violence grinds on, the international community is searching for new diplomatic approaches to stop the protracted bloodshed in Syria.
The regime's crackdown on dissent has left it almost completely isolated internationally, but Assad is receiving political backing from Russia and China, which delivered a double veto over the weekend that blocked a UN resolution calling on him to leave power.
Sanctions are crippling the Syrian economy, but they have failed to stop military offensives that have led to an overall death toll of more than 5,400 people since March.
A senior Arab League official said today that the Cairo-based organization will discuss at a meeting Sunday whether to recognize the opposition Syrian National Council as the legitimate representative of Syria and whether to allow it to open offices in Arab capitals. The official spoke on condition of anonymity because no decision has been made on the issue.
Libya joined the United States and a growing number of Arab and European countries in reducing diplomatic ties with the Syrian regime. The Libyan government gave Syria's top envoy to the country and embassy staff 72 hours to leave on Thursday in protest against the crackdown, said Libya's Foreign Ministry press officer, Saad Elshlmani.
Homs, Syria's third-largest city, has become the focus of both resistance and reprisal in the 11-month uprising as many areas have fallen under the control of increasingly bold army defectors who want to bring down the regime by force.
In the latest operation, which began Saturday, government forces have unleashed a relentless offensive against Homs, shelling residential areas as they try to root out any resistance and retake control of the city of 1 million people.
Hundreds are believed to have been killed in the heaviest bombardment the city has seen since the country's uprising began in March, activists said.
The Britain-based Syrian Observatory for Human Rights and the LCC were trying to compile numbers and names of those killed Thursday. The Local Coordination Committees, an activist group, said an estimated 90 people were killed in Homs, but the death toll was impossible to independently verify. Activists also reported violence in Zabadani and Daraa.
Also Thursday, Germany expelled four Syrian diplomats following the arrest earlier this week of two men accused of spying on Syrian opposition groups in the country.
Foreign Minister Guido Westerwelle said he ordered the expulsions of the four Syrian Embassy employees and the ambassador had been informed. He did not give details on the diplomats.
German federal prosecutors said Tuesday they had arrested a Syrian and a German-Lebanese dual national on suspicion that they spied on Syrian opposition supporters in Germany over several years.
The uprising began with mostly peaceful protest but has transformed into an armed insurgency against Assad in many areas, raising fears the country is spiraling toward a full-fledged civil war.
UN Secretary-General Ban Ki-moon said Wednesday the head of the Arab League plans to send observers back into Syria and has raised the possibility of a joint mission with the United Nations.
The UN chief provided no specifics, but the idea appears aimed at giving the regional group a boost after the league's earlier mission was pulled out of the country because of security concerns.
"In the coming days we will further consult with the council before fleshing out details," Ban said. "We stand ready to assist in any way that will contribute toward improvement on the ground."
Ban also reiterated his "deep regret" over the council's inability to speak in one voice to stop the bloodshed. Russia and China used their veto powers on Saturday to block a Security Council resolution backing an Arab League peace plan that calls for Assad to step aside.
Ban said the lack of council unity has encouraged the Syrian government to step up its attacks on civilians.
"Thousands have been killed in cold blood, shredding President Assad's claims to speak for the Syrian people," Ban said. "I fear that the appalling brutality we are witnessing in Homs, with heavy weapons firing into civilian neighborhoods, is a grim harbinger of worse to come."
China, meanwhile, said a Syrian opposition delegation visited Beijing and met Vice Foreign Minister Zhai Jun as the country insisted it wants to maintain contacts and communication with Syrian opposition groups.