The brutal crackdown on dissent in Syria continues unabated despite the signing of an Arab League peace plan last week, the United Nations human rights office reported Tuesday, adding that the death toll has now surpassed 3,500.

"We are deeply concerned about the situation and by the Government's failure to take heed of international and regional calls for an end to the bloodshed," Ravina Shamdasani, spokesperson for the Office of the High Commissioner for Human Rights (OHCHR), told reporters in Geneva.

More than 60 people are reported to have been killed by military and security forces in recent days, including at least 19 on Sunday, said Ms. Shamdasani.

While the Syrian Government announced the release of 553 detainees on Saturday on the occasion of Muslim holiday of Eid al-Adha, tens of thousands remain in detention and dozens continue to be arbitrarily arrested everyday.

In addition, Syrian troops continue to use tanks and heavy weaponry to mount attacks on residential areas in the city of Homs.

The situation in the neighbourhood of Baba Amr has been particularly appalling, said Ms. Shamdasani. According to information received by OHCHR, the neighbourhood has remained under siege for seven days, with residents deprived of food, water and medical supplies.

Last week Syria had reportedly accepted the plan proposed by the League of Arab States that included the release of prisoners, the withdrawal of security forces from the streets and talks between the Government and opposition.

Protesters began taking to the streets in Syria in March as part of a wider pro-democracy movement across North Africa and the Middle East this year that has toppled long-standing regimes in Tunisia, Egypt and Libya.