Forty-eight Iranians held hostage by Syrian rebels for five months have arrived in a Damascus hotel after being freed in a prisoner swap for more than 2,000 regime prisoners.

The Iranians, described by Iran as "pilgrims" and by the rebels as captured Revolutionary Guards members supporting Syrian forces, looked visibly exhausted on Wednesday, with some weeping, the AFP news agency reported.

They were embraced by waiting Iranian diplomats and given white lilies.

The prisoner exchange on Wednesday was the biggest to occur in Syria's 21-month old conflict.

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Several sources, including a rebel spokesman and Iranian officials, said it was arranged through mediation by Turkey and Qatar.

Earlier on Wednesday, the Turkish humanitarian aid agency IHH said that the Syrian government would free 2,130 prisoners in exchange for the Iranians.

Bulent Yildirim, the head of IHH, was in Damascus to help negotiate the deal.

"This is the result of months of civil diplomacy carried out by our organisation," Serkan Nergis, a spokesman for IHH, said.

Rebel accusation

The Iranians were captured in Damascus in August by rebel groups, who said the prisoners were members of Iran's Revolutionary Guard.

Rebels released a video showing Iranian military identification cards, allegedly taken from the captives.

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Iran denied this, saying they were pilgrims visiting a Shia Muslim shrine in Syria.

None of the freed Iranians spoke to the media about their months-long  ordeal.

Instead, the Iranian ambassador to Damascus, Mohammed Reza Shibani, said that the Iranians were kidnapped in southwestern Damascus as they travelled on the road linking the city's international airport with the Sayyida Zainab district, where an important Shia Muslim shrine is located.

He portrayed the Iranians as "pilgrims" who still wanted to see the shrine  before they left Syria.

The hostages had been a major bargaining chip for the opposition; Iran is one of Syrian president Bashar al-Assad's closest allies.

This is the first major prisoner swap since the uprising against Assad began in March 2011.

Source: Agencies