BEIRUT: A prisoner swap of 48 Iranians held hostage by Syrian rebels in exchange for more than 2,000 people detained by Damascus "exposes the extent of the Syrian regime's dependence on Tehran," a main opposition group said on Thursday.

"The Syrian regime is so shameless that it is the only regime in the world that exchanges its own citizens' freedom for the freedom of citizens of foreign states," said the Syrian National Council.

"This victory (the prisoner release) exposes the extent of the Syrian regime's dependence on Tehran," the SNC added.

Forty-eight Iranians held hostage by Syrian rebels for five months arrived in a Damascus hotel on Wednesday after being freed in a prisoner swap for more than 2,139 people held by the regime.

The prisoner exchange was the biggest to take place since Syria's conflict erupted more than 21 months ago.

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

"The Syrians' pride in this great achievement does not make them forget to thank our brothers and friends in Qatar and Turkey for their kind efforts," the SNC statement said.

Iran is a key regional ally of President Bashar al-Assad's regime.