Syria is committed to its key regional ally Iran attending a planned peace conference next month to which it has yet to be invited, Foreign Minister Walid Muallem said Sunday.

"Syria is committed to Iran joining the peace conference," the official SANA news agency quoted Muallem as saying at a media forum.

"It is illogical that the United States or the so-called opposition exclude this country from the conference for political reasons," he said.

Iran does not figure on a list named by global peace envoy Lakhdar Brahimi in Geneva on December 20 for the January 22 conference dubbed Geneva 2.

"On Iran, we haven't agreed yet," Brahimi told reporters after talks with US and Russian officials.

"It's no secret that we in the United Nations welcome the participation of Iran, but our partners in the United States are still not convinced that Iran's participation would be the right thing."

On December 23, UN chief Ban Ki-Moon said invitations to the peace talks would be sent by the end of the year and launched a fresh appeal for Iran to take part.

"The invitation list is near complete, I hope the question of Iran's participation is resolved soon," Ban told reporters.

"As I have said before, Iran needs to contribute to peace in Syria along with others in the region."

Saudi Arabia, a main backer of the rebels battling President Bashar al-Assad's forces, is among the 26 countries invited to the talks.