BEIRUT - Syria's warring parties declared a 48-hour ceasefire in a frontline area on Wednesday after a month of unprecedented mediation from Turkey and Iran, signalling a new approach by some regional powers backing opposing sides in the conflict.
The ceasefire halted fighting between insurgents on the one hand, and the army and its Lebanese militant Hezbollah allies on the other, in the rebel-held town of Zabadani and in a pair of Shi'ite Muslim villages in Idlib province.
The two areas are strongholds of each side under ferocious attack by the other, meaning both could benefit from a ceasefire by evacuating civilians or combatants.
Three officials close to Damascus described the truce as a result of mediation by Turkey, which backs rebels fighting against President Bashar Assad, and Iran, whose support has been vital to his survival.
It was among the strongest signs yet of a new regional approach towards a conflict that has killed a quarter of a million people, made 10 million homeless, left swathes of Syria in the hands of Islamic State militants and divided the countries of the Middle East on sectarian grounds.
After four years in which international diplomacy made no headway towards peace, countries that support Assad and his opponents have been quietly discussing ways to end the war and tackle the common threat from Islamic State. But Assad's fate remains a major obstacle to the new diplomatic effort.
The Iranian foreign minister was due in Damascus later on Wednesday and expected to discuss a new peace plan for Syria.
Sources on both sides of the civil war told Reuters earlier on Wednesday the truce was to begin at 6 a.m. (0300 GMT), and negotiations would continue. The rebel group Ahrar al-Sham had led the talks on the insurgents' side.
"A ceasefire began at 6 a.m. today for 48 hours to halt military operations in Zabadani," Hezbollah's al-Manar TV reported. "It also includes the two villages of al-Foua and Kefraya in the Idlib countryside."
The Syrian Observatory for Human Rights, a Britain-based group that reports on the war, said no fighting had been reported in Zabadani, Kefraya or al-Foua after the ceasefire's agreed start time.
"So far there is calm," Rami Abdulrahman, who runs the Observatory, told Reuters.
Zabadani, about 45 km (30 miles) northwest of the capital Damascus and about 10 km from the border with Lebanon, has been the focus of a weeks-long offensive by the army and Hezbollah aimed at wresting control of the town from rebels.
The two Shi'ite villages of al-Foua and Kefraya, meanwhile, have been targeted in a parallel offensive by an insurgent alliance that includes both the Sunni Islamist Ahrar al-Sham and the al-Qaida-linked Nusra Front.
The United Nations envoy for Syria said last month that government air strikes had caused widespread death and destruction in Zabadani, and expressed concern that civilians were trapped both there and in the two Shi'ite villages.
Ahrar al-Sham said last week it was holding talks with an Iranian delegation over Zabadani, located in an area of western Syria where Assad, who faces an army manpower shortage, has sought to shore up control.
A source close to the negotiations from the insurgents' side earlier told Reuters: "The ceasefire has been agreed on but there are other points and negotiations are continuing on them."
One of the officials close to Damascus said: "The ceasefire will begin and some (people) who are in critical condition will be evacuated. Talks will discuss further steps."
The source added that ongoing talks were focused on an evacuation of rebel fighters from Zabadani, and an evacuation of civilians from the two villages. ROCKETS HIT DAMASCUS AHEAD OF ZARIF VISIT
While diplomacy has so far been a total failure in ending the war, there are signs of a new push following Iran's nuclear deal last month with major powers including both the United States and Russia.
Turkey, a major regional power and opponent of Assad that until now had avoided a direct role in the war, has revamped its strategy in recent weeks to join a campaign against Islamic State. It is pressing for a buffer zone in Syria near its frontier that would be free of Islamic State and controlled by opponents of Assad.
Rebels fired dozens of rockets into Damascus on Wednesday ahead of the arrival of Iranian Foreign Minister Mohammad Javad Zarif. The Observatory said the rebel rockets on the capital killed one person and wounded 20 others, while army airstrikes killed around 30 people in nearby rebel-held areas.
An Iranian foreign ministry spokeswoman said details of a new plan for the Syria crisis would be revealed after Zarif held talks with Damascus and other players.
The Iranian nuclear talks saw the first direct, top level diplomacy between Iran and the United States since Iranian revolutionaries stormed the US embassy in Tehran in 1979. Any progress on Syria could be seen as a major example of what both foes have said might be wider diplomatic benefits.
In Iraq, the United States and Iran are both supporting the government against Islamic State, with Washington providing air support and Tehran providing aid to government-allied Shi'ite militia on the ground.
In Syria, the United States and regional powers including Turkey and Saudi Arabia say Assad must go as part of any settlement. Iran and Russia have stuck by him.
Underscoring the divide between Assad's foreign friends and enemies, Russia and Saudi Arabia failed in talks on Tuesday to overcome differences over his fate.
But the fact that such talks are taking place at all is a sign of progress after the years of diplomatic stalemate.
The war has turned Syria into a patchwork of areas run by an array of armed groups including the ultra-hardline Islamic State, a well-organised Kurdish militia, the Nusra Front and other rebels who espouse a nationalist agenda.
The Observatory estimates Assad's control at around 25 percent of Syria, including its most populous areas such as the capital, Damascus.
The government has been losing ground in several parts of the country in recent months, which Western officials say should encourage Assad to negotiate. But he showed no sign of a willingness compromise in a speech last month.