BEIRUT — Lakhdar Brahimi, the envoy trying to broker a peace deal in Syria, announced a seemingly unlikely cease-fire on Wednesday between the two sides to mark the main Muslim holiday of the year, and the UN Security Council unanimously endorsed his effort.
Numerous do-it-yourself aspects of the plan, notably its voluntary nature, immediately called into question whether it would quiet any fighting.
Other uncertainties included the time frame of what was designed to be a temporary cease-fire for the Eid al-Adha, the Islamic Feast of Sacrifice, expected to start Friday in much of the Muslim world. But different nations and sects observe the holiday from one to five days, so it was not clear how long any truce should last.
On a more basic level, it was not quite clear who would respect it among the warring parties. Syrian state television announced that Damascus was studying the proposal and would make an announcement Thursday. Various leaders among the fractious rebels issued their own statements saying they doubted it would hold.
It was also unclear how a cease-fire could be enforced or even monitored independently — the Security Council ordered the withdrawal of UN observers this summer.
Gert Rosenthal, Guatemala’s ambassador to the United Nations and the current rotating president of the Security Council, told reporters at the United Nations, ‘‘This is a voluntary cease-fire which Mr. Brahimi is promoting.’’
In a statement read by Rosenthal welcoming the proposal by Brahimi, the joint special representative for both the United Nations and the Arab League, the Security Council asked ‘‘all regional and international actors to use their influence on the parties concerned to facilitate the implementation of the cease-fire and cessation of violence.’’
The statement also said the council ‘‘called upon all parties, in particular on the government of the Syrian Arab Republic as the stronger party, to respond positively to the initiative of the joint special representative.’’ It reiterated earlier Security Council demands that the Syrian government allow ‘‘immediate, full, and unimpeded access of humanitarian personnel to all populations in need of assistance.’’
The United Nations has estimated more than 2.5 million Syrians are in urgent need of aid because of the conflict’s disruptions to their daily lives.
Brahimi seemed to be relying on both sides in the war, which grew out of a peaceful protest movement that started in March 2011, to respect the cease-fire on their own.
Speaking at a news conference in Cairo before he privately briefed the Security Council via a video link, Brahimi said the Syrian government was poised to announce the cease-fire and that the rebel factions he was in contact with had promised to respect it as well.
“Other factions in Syria that we were able to contact, leaders of fighting groups, most of them also agreed on the principle of the cease-fire,’’ Brahimi said after briefing Nabil Elaraby, the secretary general of the Arab League.
Brahimi replaced Kofi Annan in September as the Syria peace envoy after Annan resigned in frustration over the lack of progress toward peace.
“We hope that we can build on this initiative to be able to talk about a real cease-fire, a longer and stronger cease-fire,’’ Brahimi said.
Rebel commanders noted that while the regime of Syrian President Bashar Assad in Damascus was ostensibly talking about a cease-fire, its forces were busy shelling rebel fighters and civilians in various cities, including Qusayr outside Homs and Maaret al-Noaman near Idlib in the north.
The prevailing opinion among rebel commanders seemed to be that the government was agreeing to a cease-fire only as a tactical measure to regroup to try to reverse wide rebel gains, especially in the north.