George Sabra, the new head of the main Syrian opposition bloc in exile, the Syrian National Council, speaks to reporters during a press conference on the sidelines of the General Assembly of the Syrian National Council meeting in Doha, Qatar, Saturday, Nov. 10, 2012. (Osama Faisal/AP)

Fractious Syrian opposition groups finally struck a deal Sunday to form a new umbrella organization after a week of heated negotiations that were nearly derailed on several occasions.

The new organization, called the National Coalition for Revolutionary Forces and the Syrian Opposition, is intended to act as the single entity that manages the political and military affairs of the opposition and as the conduit for humanitarian and military aid.

At the end of October, Secretary of State Hillary Rodham Clinton said the Syrian National Council, the opposition group formed in August 2011, could no longer claim to be the credible leader of the opposition.

In recent months, the SNC has been criticized as an ineffectual organization out of touch with events on the ground in Syria.

Although many details of the structure of the new coalition and the timeline for achieving its political goals remained largely undefined Sunday, international supporters of the opposition praised the agreement and highlighted what appeared to be a new willingness of activists to work together.

A Syrian opposition conference held in Cairo in July led to fistfights between some activists.

“The regime fears most that the opposition unifies,” said Riyad Hijab, the former Syrian prime minister who defected in August and attended the opposition conference last week. “I know that. I was part of that regime.”

International backers of the opposition hope that a credible leadership for the group could win the support of ordinary Syrians and reduce the influence of extremist groups that are on the rise in the country.

At the signing ceremony for the new coalition, which ran past midnight Sunday, many of the Western supporters of the opposition were cautiously optimistic.

“I am hopeful that this will get traction in Syria,” said a Western diplomat who spoke on the condition of anonymity because of the sensitivity of the subject. “But it’s the Syrians who must decide.”

Moaz Khatib, former imam of the Umayyad Mosque in Damascus, was named president of the new coalition. Khatib, who appeared at the signing ceremony Sunday night wearing a gray suit rather than clerical robes, is viewed as a religious moderate and is widely respected by opposition members inside and outside Syria. Riad Seif, a longtime activist who led the initiative to start a new coalition, and Suhair Atassi, a prominent female activist, were named vice presidents.

“After long suffering, the multiple national forces have reached a coalition of one front to help our people who are being slaughtered every day on the watch of the world,” Khatib said at the signing ceremony, which was attended by Turkish Foreign Minister Ahmet Davatoglu and Qatar’s prime minister, Hamad Bin Jasim al-Thani.

The leaders of the coalition said that gaining international recognition was a top priority and that Khatib may head to Cairo as soon as Monday to pursue recognition from the Arab League.

That would be followed by a push to get recognition from the Friends of Syria group, which includes the United States, followed by a pitch to the United Nations.

International recognition could allow the coalition to receive frozen Syrian government funds, take over Syrian embassies and even pursue the seat of the Syrian government at the Arab League, activists said.

Many prominent activists said they had received repeated assurances from their foreign backers that they would receive recognition quickly.

The urgency of the work ahead for the coalition was highlighted by attacks across Syria on Sunday that killed at least 90 people, according to the Local Coordination Committees, an activist network.

The Syrian military used helicopters and tanks Sunday to attack the town of Ras al-Ain, which is on the border with Turkey, the Associated Press reported.

At least 11,000 Syrians fled intense clashes between government forces and rebels in Ras al-Ain on Thursday, according to the United Nations.

One of the most contentious issues in the discussions at the conference was the SNC’s role.

Some members of the SNC pushed back hard against the initiative to form the new coalition, fearing it would mean the dissolution of their group. But many of the holdouts stood down under strong pressure from their colleagues who backed the initiative and the opposition’s foreign supporters.

The SNC was offered additional seats to win its support, and it will receive about one-third of the 60 seats in the new coalition. About one-quarter of the seats will be set aside for members from inside Syria, which will include a representative from each of the country’s 14 provinces.

“The most important components are those coming from inside Syria, and they’re fully on board,” said Yaser Tabbara, a founding member of the SNC who helped shape the initiative to form the new coalition.

Provisions also have been made to include minorities in the new organization.

The new coalition will function as a sort of parliament rather than a government, according to participants in the discussions, and will be responsible for the creation of a legal committee, a military council and a temporary government.

The formation of the military council, which will include representatives from the Free Syrian Army as well as local militias and defectors, may be the most important step for the new coalition.

The distribution of military aid to armed groups in Syria has been chaotic and led to infighting among various factions. Now, the countries giving military aid, which include Qatar and Saudi Arabia, have decided to channel the weapons through a central body that could establish some control over the process.

“The whole point of establishing this political umbrella . . . is to act as that civic point of authority for the military people,” Tabbara said.

The coalition will not engage in dialogue or negotiations with the Syrian government, according to a draft document for the creation of the body released Sunday.

Activists who participated in the meetings said the deal is an important breakthrough, but many acknowledge that there will be tough negotiations ahead.

“This is an important step, but the devil will be in the details,” the Western diplomat said.