The cease-fire in Syria came into effect at 6 a.m. local time (0300 GMT) on Thursday in compliance with a deadline set by UN-Arab League envoy Kofi Annan.

In line with a pledge from the Syrian regime and opposition rebels to uphold the UN-brokered deal, activists reported no major incidents of violence as the deadline passed. They, did however, say they had not seen any evidence of Syrian forces withdrawing from flashpoint cities, which the cease-fire agreement had stipulated.

"There are no signs of a pull back - the tanks, snipers and armed forces are still visible across the city," an activist from Homs who called himself Abu Rami, told the Reuters news agency.

The opposition Free Syrian Army commander Riad al-Asaad on Wednesday told Al Jazeera television his group had "expressed their commitment to Annan's initiative."

Meanwhile, the official Syrian News Agency SANA quoted a Defense Ministry source as saying that all military operations would be suspended by the deadline. The source stipulated, however, that "the armed forces will be on alert to confront any attack by armed terrorist groups against civilians, law-enforcement members, the armed forces and private and public facilities."

Just hours before the deadline expired, the London-based Syrian Observatory for Human Rights said that numerous people were killed in Damascus, Homs and a near the Lebanese border.

International skepticism

As reports of violence continued to emerge late on Wednesday and into the early hours of Thursday morning, western leaders voiced skepticism over whether the cease-fire would mark an end to 13 months of bloodshed.

According to a White House statement, US President Barack Obama and German Chancellor Angela Merkel agreed in a telephone call that the UN Security Council needed to "take more resolute action" on Syria.

"The president and chancellor shared the concern that the Assad government was not complying with the terms of the agreement negotiated by Kofi Annan and continued to engage in unacceptable brutality against its own people," the statement said.

As the G8 countries held talks in Washington, Britain and France also expressed doubts regarding Syria's commitment to upholding the peace plan, pressing for monitors to verify the cease-fire.

The UN Security Council must seek a "robust observers force" that would verify compliance and "could move freely" throughout Syria without interference from Assad's regime, French Foreign Minister Alain Juppe said.

British Foreign Secretary William Hague added that his government would boost support for Syria's opposition and seek further sanctions if Assad does not comply with the cease-fire.

ccp, ncy/ ng (AFP, AP, Reuters, dpa)