Nearly 50 Iranians headed home after being freed by Syrian rebels in a prisoner swap were stranded on Thursday at the Damascus airport by bad weather that has swept the Middle East.

In northern Syria, rebels linked to the al-Qaida terrorist network battled army troops inside a military helicopter base in Idlib province.

The rebels freed 48 Iranian captives on Wednesday in exchange for more than 2,000 prisoners held by Syrian authorities. It was the first major prisoner swap since the uprising against President Bashar Assad began nearly 22 months ago.

A Syrian official said the Iranians left the Damascus Sheraton hotel early Thursday. But the plane to take them home after months in captivity could not take off because of strong winds from a fierce winter storm that has hit the region in recent days. An airport official said a Syrian plane was waiting to take the Iranians home later in the day.

The officials spoke on condition of anonymity because they were not authorized to give information to the media.

Rebels claimed the captives were linked to Iran's powerful Revolutionary Guard, but Tehran has denied that, saying the men were pilgrims visiting Shiite religious sites in Syria.

U.S. State Department spokeswoman Victoria Nuland described most of the Iranians as "members of the Iranian Revolutionary Guard," calling it "just another example of how Iran continues to provide guidance, expertise, personnel, technical capabilities to the Syrian regime."

Iran is one of Assad's main allies, and the Iranians, who were seized outside Damascus in August, were a major bargaining chip for factions trying to bring down his regime in the civil war that has killed more than 60,000 people.

In the past weeks, rebels have captured large areas in the north of the country along Syria's border with Turkey and in towns and villages around Damascus. The opposition fighters have also overrun several military bases, seizing weapons and ammunition from government forces, which outgun rebels with fighter jets and helicopter gunships.

The Britain-based Syrian Observatory for Human Rights said the rebels entered the Taftanaz air base in Idlib province late Wednesday. The Observatory said clashes between the troops and rebels inside the base continued Thursday, adding that the rebel assault was led by the al-Qaida-linked Jabhat al-Nusra fighters.

The U.S. has designated the group as a terrorist organization.

Rebels have battled army troops for weeks for control of the Taftanaz base where helicopters and war planes take off on missions to bomb rebel-held areas around the country.

The Syrian opposition and fighters on the ground have repeatedly asked their backers in the West for anti-aircraft missiles to fight Assad's deadly airpower.

On Thursday, government jets carried out an airstrike on rebels' positions within the Taftanaz base, the Observatory said, adding that airstrikes also hit the rebel-held eastern Ghouta district. The district is an opposition stronghold near Damascus from which rebels have been be conducting an offensive on the seat of Asaad's power in the capital.


Surk reported from Beirut.