Iraqi Shia Muslims are fighting in Syria alongside troops of President Bashar al-Assad, Iraqi Foreign Minister Hoshyar Zebari said on Friday, while insisting this was not the policy of the Shia-led Baghdad government.

"I do not deny that Iraqi Shia fighters are participating in combat in Syria, just as Sunnis from the Gulf are doing in that country," he said in remarks published by pan-Arab daily Al-Hayat.

"But that does not come under government policy," added Zebari, himself a Kurd and a Sunni Muslim.

At a Friday news conference in Stockholm, he said he had "no first hand figures" on the number of Iraqi Shia ighters in Syria, but that there were "not several thousand... maybe several hundred".

Fighters from Lebanon's Shia Hezbollah movement have also intervened in Syria alongside troops loyal to Assad, whose Alawite sect is an offshoot of Shiite Islam.

Their presence has been roundly denounced by rebels fighting to overthrow Assad, most of whom come from Syria's Sunni majority, and by influential Egyptian-born cleric Sheikh Yusef Qaradawi.

While "Hezbollah militia are engaged in combat in Syria, there are also Sunni fatwas, such as the one by Qaradawi calling for jihad in Syria," Zebari said.

At the beginning of June, the Qatar-based cleric called on Sunni volunteers from around the Muslim world to fight alongside the rebels.

"The Syrian conflict has become more dangerous, because the sectarian confrontation has been brought to the fore. This is very dangerous and I think all countries should be aware not to push things in this direction," Zebari said in Stockholm.

The uprising that broke out more than two years ago is increasingly becoming a sectarian battle between Sunnis, supported by rich Gulf monarchies, and Shiites, supported by Iran.