Syrian peace talks could collapse before they even start, with the main opposition coalition bloc issuing a deadline for the withdrawal of Iran's invitation to the talks.
The Syrian National Coalition, a key player in the so-called Geneva II meeting, set to start on Wednesday, has given a deadline of 19:00 GMT on Monday for Tehran's invitation to be rescinded. It is furious about the United Nations' overtures to Iran, which is an ally of President Bashar al-Assad.
A statement issued by the Coalition demanded a "clear public commitment" from Iran to pledge a withdrawal of all its troops and militias from Syria, explicit support for all the terms in the 2012 Geneva I communique and a positive commitment to Geneva II.
"In case of failure to obtain the pledge, we ask the SG Ban Ki-Moon to rescind/withdraw its invitation to Iran. Otherwise, the Syrian Coalition will not be able to attend the Geneva 2 conference," said the statement.
Earlier on Monday, Anas Abdah of the Coalition's political committee told Al Jazeera that the bloc was "surprised" by UN Secretary-General Ban Ki-moon's invitation, saying: "It is illogical and we cannot in any way accept it."
Ban said Iran's Foreign Minister Mohammad Javad Zarif had promised his country would play a "positive and constructive role" if it were asked to participate.
"He has assured me that, like all the other countries invited to the opening-day discussions in Montreux, Iran understands that the basis of the talks is the full implementation of the 30 June, 2012, Geneva communique," he said.
However, Iran's Press TV reported on Monday that Tehran would participate in the upcoming Geneva II conference on the Syria crisis without accepting crucial elements of the 2012 Geneva communique.
The Iranian news agency ISNA quoted the spokeswoman for Iran's Foreign Ministry, Marzieh Afkham, as saying: “We have always rejected any precondition for attending the Geneva II meeting on Syria. Based on the official invitation that we have received, Iran will attend the Geneva II without any preconditions.”
The ensuing confusion and dispute surrounding Iran's invitation prompted Ban to tell the UN Security Council on Monday that "intensive and urgent discussions" were under way.
"For the moment, let me just appeal again to all involved to keep the needs of the Syrian people foremost in mind," the Secretary-General told the 15-member Security Council.
'Unqualifed to attend'
Saudi Arabia, which backs Syrian opposition forces, has also rejected Iran's participation in Geneva II.
On Monday in an official statement it said that Iran did not "announce officially and openly its agreement [to]... the creation of a transitional government" and that this position rendered Tehran "unqualified to attend."
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The disputes and threats regarding attendance come as Assad said he was likely to run in June's presidential race.
The Syrian president said on Sunday there was a "significant chance" he would make a candidacy bid.
"I see no reason why I shouldn't stand," he said. "If there is public opinion in favour of my candidacy, I will not hesitate for a second to run for election."
The Swiss meeting is backed by both the United States, which supports the rebels, and Russia, an Assad ally.
"The Geneva conference must lead to clear results regarding the fight against terrorism," Assad said in an interview with the AFP news agency.
"Any political result that did not include the fight against terrorism would have no value," said Assad, who is embroiled in an almost three-year-old war with rebels fighting to topple him.
Assad also ruled out that the Istanbul-based Syrian National Coalition to be given any ministerial positions in a new government, calling it "totally unrealistic."
Syrian opposition groups and the US, which accuse Iran of supporting Assad with manpower and arms during the conflict, have long had reservations about the participation of Iran, although Ban and the UN special envoy on Syria, Lakhdar Brahimi, are backing Iran's involvement.
A US State Department official, speaking on condition of anonymity, said of Iran on Monday: "They are doing nothing to de-escalate tensions ... and their actions have actually aggravated them, and so the idea that they would come to the conference refusing to acknowledge support for Geneva 1, we do not see how it could be helpful."
Another US administration official said: "Iran has not publicly endorsed Geneva, not before last night and not overnight. We expect the invitation will be rescinded."