United Nations officials said Tuesday the death toll in Syrian President Bashar al-Assad's brutal crackdown has topped 3,500.

"The brutal crackdown on the dissents in Syria has so far claimed the lives of more than 3,500 Syrians," said Ravina Shamdasani, spokeswoman for the UN High Commissioner for Human Rights.

"More than 60 people are reported to have been killed by military and security forces since Syria signed the peace plan sponsored by the league of Arab states, including at least 19 on Eid al-Adha on Sunday," she added.

President Bashar Assad's government signed on to an Arab League plan aimed at stopping the seven plus months of unrest in his country on November 2.

The Arab plan calls for an end to violence, the release of political detainees, the withdrawal of the army from urban areas, free movement for observers and the media, and talks between Assad's regime and opposition. 

Syria announced Saturday it had released more than 550 people who were arrested during anti-regime protests, to mark the Eid al-Adha Muslim feast. 

However, Shamdasani noted that despite the release, "thousands continue to remain in detention and dozens continue to be arbitrarily arrested every day." 

"Syrian troops continue to use tanks and heavy weaponry to attack residential areas in the city of Homs," she said, referring to the flashpoint central city where protests against Assad's rule continue to be held despite a weeks-long military crackdown.

"This has been extraordinarily disappointing," said the spokeswoman.

"There was a peace plan by the league of Arab states that the Syrian government had engaged to, but since the peace plan was signed, there have been further killings, further sieges of towns and really shocking reports coming out from the ground," she noted.