Activist preacher Moaz al-Khatib

Moderate … former imam Moaz al-Khatib. Photo: Reuters

DOHA, Qatar: Syria's opposition has agreed to unite against the President, Bashar al-Assad, and elected a cleric as its first leader, as Israel fired warning shots into the country after mortar fire hit the Israeli-occupied Golan Heights.

After days of marathon talks in Qatar, the Syrian National Council finally signed up to a wider, more representative bloc centred on a government-in-waiting, as demanded by Arab and Western states.

Moaz al-Khatib, 52, the imam of the historic Umayyad mosque in Damascus, who quit Syria three months ago, was elected to head the new body. Reservations in Syrian National Council ranks about what many members saw as a move to sideline it had prompted repeated delays in the talks and mounting frustration among other dissident groups and the opposition's Arab and Western supporters.

But after negotiations ran into the early hours of Sunday and resumed in the afternoon, the anti-Assad factions agreed to form a ''National Coalition of Forces of the Syrian Revolution and Opposition''.

''We signed a 12-point agreement to establish a coalition,'' said the leading dissident Riad Seif, who drew up the US-backed reform proposals on which Sunday's agreement was based.

The document said the parties ''agree to work for the fall of the regime and of all its symbols and pillars'', and ruled out dialogue with the regime.

They agreed to unify the fighting forces under a supreme military council and to set up a national judicial commission for rebel-held areas.

A provisional government would be formed after the coalition gained international recognition, and a transitional government formed after the regime fell.

The former prime minister Riad Hijab, who fled to neighbouring Jordan in August in the highest-ranking defection from Mr Assad's government, hailed the agreement as ''an advanced step towards toppling the regime''.

''The regime fears most that the opposition unifies,'' Mr Hijab said.

''I know that. I was part of that regime.''

International backers hope a credible leadership for the group could win the support of ordinary Syrians and reduce the influence of extremist groups.

''What we're looking for is an organisation that can have credibility in the eyes of Syrians in Syria,'' said a Western diplomat who asked not to be identified.

Its supporters are pushing for quick international recognition, perhaps even before the process of selecting all the members of the body is complete, to receive frozen Syrian government funds, take over Syrian embassies and even pursue Syria's seat at the Arab League. But it is the formation of the military council, which will include representatives from the Free Syrian Army as well as local militias and defectors, which may be the most important step.

The distribution of military aid has been chaotic and led to infighting among various factions.

Now the countries giving aid, which include Qatar and Saudi Arabia, have decided to channel weapons through a centralised body that could establish some degree of control.

The Israeli warning shot across the UN-monitored ceasefire line between Syria and the occupied Golan Heights came after a mortar round fired from the Syrian side hit an Israeli position.

Military sources said the Israeli army fired a single Tammuz anti-tank missile, a weapon known for being highly accurate, towards the Syrian outpost from which the mortar round was fired.

''We shot towards them, but deliberately missed,'' one said.

The chief military spokesman, Yoav Mordechai, said it was Israel's first firing across the armistice line since the 1973 Yom Kippur war.

The Defence Minister, Ehud Barak, warned any more fire from Syria would elicit ''a tougher response, exacting a higher price from Syria''.

Agence France-Presse, The Washington Post