Beirut - The head of Syria's main opposition bloc, Burhan Ghalioun, formally resigned from his post, a statement issued by the Syrian National Council said on Thursday after a two-day meeting in Istanbul.
The SNC "office decided to accept the resignation and to ask the council president to pursue his work until the election of a new president at a meeting on June 9-10", it said.
Ghalioun announced his resignation on 17 May to avert divisions within the opposition bloc, after activists on the ground accused him of monopolising power.
The statement also said Syria's unwillingness to stick to a peace deal brokered by UN-Arab League envoy Kofi Annan and the continuing shelling and killing in the country were "a deliberate attempt to scupper the plan".
It called on "the international community to immediately act to adopt a new mechanism, through the [UN] Security Council, to force the Syrian regime to put an end to its crimes because as it is this regime only reacts to force".
The bloodshed comes despite a more than month-old ceasefire crafted by Annan as part of a plan aimed at ending violence that has swept Syria since March 2011 when a popular revolt erupted against the regime of Bashar al-Assad.
The plan includes the deployment in flashpoint areas of around 300 UN observers.
Ghalioun, who had led by consensus rather than through election since the SNC's founding in October, was elected as the exile group's chairperson in a vote held in Rome on 15 May.
He said after announcing his plan to step down that he would remain an SNC member "hand-in-hand with the young people who struggle, the young people of the revolution of dignity and freedom, until victory", while urging all opposition groups to unite ranks.
Hours earlier, the Local Co-ordination Committees (LCC), a network of activists on the ground, threatened to pull out of the SNC over its lack of collaboration with activists in Syria and "monopolisation" of power.
The LCC also criticised the SNC over the strong influence that Syria's Muslim Brotherhood wields over the coalition.
More than 12 600 people, the majority of them civilians, have died since the Syrian uprising began, according to the London-based Syrian Observatory for Human Rights, including nearly 1 500 since the putative UN-backed truce took effect on 12 April.