The Arab League on Saturday suspended Syria until President Bashar al-Assad implements an Arab deal to end violence against protesters, and called for sanctions and transition talks with the opposition.

Syrian envoy Yussef Ahmad denounced the move as illegal, saying Damascus had already implemented the deal and accusing the United States of ordering the suspension.

He also charged that the League was trying to "provoke foreign intervention in Syria, as was the case in Libya."

US President Barack Obama praised the move, and EU foreign policy chief Catherine Ashton expressed her full support. The opposition Syrian National Council said it was a "step in the right direction."

A statement, read by Qatari Prime Minister Hamad bin Jassem Al-Thani, said the League had decided "to suspend Syrian delegations' activities in Arab League meetings" and to implement "economic and political sanctions" against Damascus.

Sheikh Hamad said the suspension would last "until the total implementation (by Syria) of the Arab plan for resolving the crisis accepted by Damascus on November 2."

In the Syrian capital, angry demonstrators broke through the gates of the Qatari embassy and took down the country's flag, replacing it with a Syrian one.

Ahmad insisted to reporters in Cairo that Damascus had "implemented all the articles of the agreement," even though at least 125 people have reportedly been killed in the flashpoint city of Homs alone since the deal was inked.

"It was clear (the decision) was decided through a US order," he said, accusing the League of working to an "American agenda."

Under the deal, the regime had agreed to release detainees, withdraw the army from urban areas, allow free movement for observers and media and negotiate with the opposition.

Ahmad also said the moves decided by League foreign ministers in a vote of 18-3, with one abstention, "put an end to joint Arab action and show that the (League's) administration is subjected to US and Western agendas."

Obama said he applauded the "important decisions taken by the Arab League today, including the suspension of Syria's membership", in a statement issued from Hawaii, where he is hosting an Asia-Pacific summit.

"After the Assad regime flagrantly failed to keep its commitments, the Arab League has demonstrated leadership in its effort to end the crisis and hold the Syrian government accountable," he said.

"These significant steps expose the increasing diplomatic isolation of a regime that has systematically violated human rights and repressed peaceful protests."

Washington ditched its earlier strategy of engagement after Syrian government forces unleashed a fierce crackdown on demonstrators, which the United Nations says has claimed more than 3,500 lives.

Washington says Assad has lost legitimacy and must step down. It wants to see Syria trace a similar political transition to other states caught up in the Arab Spring uprisings that are reshaping the Middle East.

A spokesman for the EU's Ashton said, "We fully support the decisions taken by the Arab League today which show the increasing isolation of the Syrian regime."

Diplomats have said the EU is readying a freeze on European Investment Bank credits and technical assistance to Syria as it mulls further sanctions on Assad's regime after months of bloodshed.