Istanbul: Syria’s opposition, under pressure to broaden its Islamist-dominated leadership, struggled to overcome deep rifts on Thursday and form a united front for a proposed international conference to try to end the Syrian war.

Delegates at talks in Istanbul agreed to add 14 members of a liberal bloc led by veteran figure Michel Kilo to the 60-member assembly of the Syrian National Coalition, the closest body that Syrian President Bashar Al Assad’s foes have to an overall civilian leadership in the two-year-old uprising against him.

That partial breakthrough followed seven days of talks and required the intervention of Turkey and Western and Arab nations. They fear that unless deep fissures in the opposition ranks are healed, the chances of a successful Geneva peace conference soon, sponsored by Russia and the US, are slight.

But many hurdles remain in the process to choose new leaders for a coalition that has been rudderless since March and to name a provisional government that could strengthen what are now weak links with rebel units inside Syria.

A US State Department spokeswoman said there was no deal yet but the coalition was working on one and Washington was “hopeful that the opposition will vote to elect leadership and to come to a conclusion on how they will expand their membership”.

The coalition is controlled by the powerful Muslim Brotherhood and a faction loyal to Mustafa Al Sabbagh, a businessman who has been Qatar’s point man for channelling financial and armed support to the opposition.

Thursday’s announcement would give Kilo’s bloc 14 seats, short of the 25 he had demanded, and also add more allies of Sabbagh’s and other factions to the assembly. It has yet to be finalised.

Kilo sounded optimistic. “We have reached an agreement. I think we need some time to prepare before we embark on the leadership selection process,” he said.

But a formal vote to approve Kilo’s bloc entry was delayed late on Thursday and negotiations stretched into another night.

A member of the Al Sabbagh bloc said: “Internal procedures must be respected and Kilo cannot be allowed to shove his way into the coalition.”

Sabbagh and Kilo are also negotiating the admission of 14 other members of activists’ groups inside Syria and finding a neutral mechanism to choose them.

Agreement has yet to be reached on Free Syrian Army demands to be represented in the coalition, sources said.

The shape of the new coalition, if it is formalised, could lessen the dominant influence of Qatar and give Saudi Arabia more influence in opposition politics as Riyadh backs the Kilo bid and improves its ties with the brotherhood.

Lebanese Shi’ite guerrillas from Iranian-backed Hezbollah are openly fighting alongside government forces in Syria. Opposition sources say Saudi Arabia is keen to play a greater role in backing the Sunni-led opposition against Al Assad, who belongs to the Alawite sect, an offshoot of Shi’ite Islam that has controlled Syria since the 1960s.

Kilo, a multi-lingual, soft-spoken former political prisoner, came out of the meeting room accompanied by a senior official of the Muslim Brotherhood, which lent de facto support to Kilo in the haggling over the expansion of the assembly.

The Brotherhood has good links with Qatar and is also influenced by Turkey which gave Brotherhood members fleeing President Hafez Al Assad’s repression refuge in the 1980s.

Kamal Al Labwani, a maverick member of the coalition, said a rapprochement between the liberal and Islamist wing of the opposition could help it undercut Russian attempts to have figures among the representatives of the opposition at Geneva who are willing to allow Al Assad to stay in power.