BEIRUT (AP) _ Syrian rebels have ignited a new front outside the capital, Damascus, in the first significant fighting there since regime forces swept over the suburbs weeks ago. The clashes highlight the shifting nature of Syria's conflict, with rebels lying in wait to rise up when the regime turns its guns elsewhere.

   The return of violence to the Damascus suburbs on Friday raises questions about how long troops can control areas before they re-erupt. Though government forces have shown they can crushed armed fighters, the regime has appeared unable to conduct major offensives in more than one place at once.

   That points to the likelihood that a conflict that is now a year old and is estimated to have killed more than 8,000 could grind on as it slides closer to a civil war.

   Diplomatic efforts have so far brought no result, but U.N. envoy Kofi Annan told the Security Council in a briefing Friday that he was determined to continue his mission and would return to Damascus. Talks last week between Annan and Syrian President Bashar Assad in Damascus saw no progress in attempts to cobble together peace talks between the two sides.

   After the confidential briefing via videolink, Annan told reporters in Geneva that he urged the council ``to speak with one voice as we try to resolve the crisis in Syria.'' Russia and China have blocked council action against Assad's regime.

   ``The first objective is for all of us to end the violence and human rights abuses and the killings and get unimpeded access for humanitarian access to the needy, and of course the all-important issue of political process that will lead to a democratic Syria,'' Annan said.

   Both Assad and much of the opposition spurned Annan's appeal for talks.

   Russian Foreign Minister Sergey Lavrov said Moscow and Beijing were pressing Assad to cooperate and that other countries should do the same with the opposition, which he accused of stonewalling the U.N. mission. ``Other Security Council members also need to do their part of the work and urge the opposition not to provoke the exacerbation of tensions,'' he said.

   Syria's Foreign Ministry said in a letter sent to the U.N. Security Council on Friday that Damascus will continue its crackdown. But the ministry also said it will cooperate with Kofi Annan, the envoy charged with trying to help end the violence in Syria.

   As the battles continue on the ground, the country's diplomatic isolation has grown. Saudi Arabia, Kuwait and Bahrain announced they will close their embassies in Syria, months after they withdrew their ambassadors from Damascus, the state-run Saudi Press Agency said. Turkey urged its citizens in Syria to return home Friday, saying some consular services will be halted in Damascus next week.

   Turkish Prime Minister Recep Tayyip Erdogan also said his country is considering creating a buffer zone inside Syria to help protect people fleeing.

   In a further attempt to cut off Assad's regime, Washington told the Iraqi government that Iran may be ferrying weapons to its ally Syria with cargo flights over Iraq. The U.S. asked Baghdad to take steps to cut off its airspace to any such flights.

   State Department spokeswoman Victoria Nuland said Iranian arms exports are banned by a U.N. Security Council resolution, adding, ``Any arms sent to the Syrian regime at this time would obviously be used in the brutal repression that the regime is exacting on its own people.''

   In recent weeks, Syrian forces have waged a series of heavy offensives against the main strongholds of the opposition _ Homs in central Syria, Idlib in the north and Daraa in the south. In the assaults, the regime has seemed to depend on select units and has relied heavily on the minority Alawite sect, to which Assad and the ruling elite belong. That may be out of worries over signs that some Sunni army conscripts have refused to fire on civilians. Sunnis are the majority in the country of 22 million and make up the backbone of the opposition.

   In early February, Assad's troops launched a major military campaign to bring the Damascus suburbs fully under government control. But they soon turned their attention to driving rebels out of other flashpoints, including the Baba Amr district of Homs and Idlib in the north.

   On Friday, activists reported that the Damascus suburbs ignited again.

   Armed rebels clashed with government troops for hours from Thursday night into Friday in Tal, on the northern outskirts of the capital, as well as two other suburbs, Dumair and Qatana, the British-based Syrian Observatory for Human Rights said.

   Syria-based activist Mustafa Osso said there were casualties. Syria restricts independent media coverage, making it difficult to confirm events on the ground and death tolls.

   ``Every time the regime controls a specific area we witness clashes in new regions,'' Osso said. ``It seems that this is the strategy of the Free Syrian Army.''

   Similar clashes erupted in the eastern oil-rich province of Deir el-Zour, bordering Iraq, according to the Observatory and another activist group, the Local Coordination Committees. Troops also clashed with gunmen in two villages in the northern region of Jabal al-Zawiya, the state news agency SANA said.

   The Free Syrian Army is a loosely organized umbrella group of army defectors and opposition supporters who have taken up weapons. The regime says it is fighting foreign terrorists and armed gangs, denying there is a popular will behind the revolt. But Assad's opponents say they have been forced to carry weapons because the government used tanks, snipers and machine guns to crush peaceful protests.

   The LCC said 40 people were killed in violence across the country Friday, including six in the suburbs of Damascus, eight in Homs and seven in Daraa. The numbers could not be immediately confirmed with other activist groups.

   Troops also clashed with army defectors in the northern Idlib province Friday, activists said. The fighting erupted in the town of Maaret al-Noman between government troops and army defectors. The Observatory said three soldiers died.

   Tens of thousands of people held protests against the regime in many Syrian towns and cities after weekly Muslim prayers, in the northern city of Aleppo, Syria's largest, to the central regions of Hama and Homs, and the southern province of Daraa.

   Security forces opened fire on several demonstrations, killing at least one person, the Observatory and LCC reported. An amateur video posted online showed hundreds of people marching in the northern city of Raqqa shortly before they came under fire. Demonstrators carried away at least two wounded people. The video could not be independently verified.

   Regime forces also shelled the rebel-held central town of Rastan, north of Homs, killing at least two people, the Observatory and LCC reported.