Syrian rebels assaulted a checkpoint in a pro-government suburb of Damascus on Saturday, setting off a suicide vehicle bomb that killed 16 soldiers, activists said.
The violence came a day after nine Shi'ite pilgrims from Lebanon kidnapped in Syria last year were freed as part of a negotiated hostage deal that could see two Turkish pilots held by Lebanese militants and dozens of Syrian women held in Syrian government jails released.
Lebanese Interior Minister Marwan Charbel said that the Syrian opposition had demanded that the female detainees be taken to Turkey. He said once that that issue was resolved then the complicated, multilateral exchange would be complete.
"We are speaking with the Syrians about this issue and, God willing, when this logistical matter ends the whole process will end," Charbel told the Al-Manar TV channel of Lebanon's Hezbollah group.
While details about the deal remained murky, it appeared to represent one of the more ambitious negotiated settlements to come out of Syria's civil war, now in its third year, where the contenting sides remain largely opposed to any bartered peace.
The pilgrims, who according to Charbel crossed into Turkey late on Friday, were part of a group of 11 hostages taken by a rebel faction in northern Syria in May 2012. Two were later released, but the nine had been held since, causing friction in the region and sparking the August kidnapping in Beirut that saw two Turkish Airlines pilots abducted.
The two Turkish Airlines pilots, previously identified as Murat Akpinar and Murat Agca, were kidnapped after flying into Beirut from Istanbul on 9 August. Lebanon's state news agency reported that a group called Zuwaar al-Imam Rida, a name implying a Shiite affiliation, claimed responsibility for the kidnapping. The group said the pilots "will only be released when the Lebanese hostages in Syria return," referring to the Shiite pilgrims.
The pilgrims were kidnapped while on their way from Iran to Lebanon through Turkey and Syria. Militants kidnapped them shortly after they crossed the Turkish border into Syria.
Meanwhile, outside Damascus, rebels led by the al-Qa'ida-linked Jabhat al-Nusra or Nusra Front set off the bomb while assaulting a checkpoint near the town of Mleiha adjoining the suburb of Jaramana, the Britain-based Syrian Observatory for Human Rights reported. It reported heavy fighting after the blast.
The state news agency SANA confirmed the suicide blast in Jaramana and said it wounded 15 people, most of them seriously.
Rebels control much of the countryside around Damascus but Jaramana, a Christian and Druse area, is mostly loyal to President Bashar Assad. Opposition fighters have previously targeted it with bombings and mortar rounds.
Assad has drawn support from Syria's ethnic and religious minorities, including Christians and members of his Alawite sect. The rebels are dominated by Syria's Sunni Muslim majority.
At least 100,000 Syrians have been killed in the civil war.