The chances of Syria peace talks in Switzerland succeeding without the participation of Damascus ally Iran are "not that great", a senior Iranian official said on Tuesday.

Deputy Foreign Minister Abbas Araqchi's comments to state television came a day after the United Nations abruptly withdrew Tehran's invitation to Wednesday's conference over its refusal to back calls for a transitional government to end the war in Syria.

Iran must openly support the creation of a Syrian transitional government if it wants a seat at this week's peace talks in Geneva, France's foreign minister warned on Monday.

"Participation in Geneva II is conditional upon explicitly accepting" the goals set out in the U.N. invitation to the talks, namely "the establishment of a transitional government in Syria with full executive powers," Laurent Fabius said in a statement.

Iran on Monday halted production of 20 percent enriched uranium, marking the coming into force of an interim deal with world powers on its disputed nuclear program.

The U.N. atomic watchdog confirmed that Iran's partial nuclear freeze, part of a landmark deal struck in November with the P5+1 powers -- the U.S., China, Russia, France, Britain and Germany -- began on Monday as planned.

Iran has called on participants at next week's international peace conference on Syria to adopt a "realistic view" and decision that will not embolden jihadist fighters, media reports said Sunday.

More than 35 countries will gather in the Swiss cities of Montreux and Geneva from Wednesday, but Syria's main regional ally Iran has not been invited to attend the conference known as Geneva II.

Iran's Foreign Minister Mohammad Javad Zarif said Sunday he was hopeful the implementation of a landmark deal with world powers would lead to a lasting agreement over Iran's nuclear drive.

The deal clinched in Geneva in November and finalized last week is to go into effect on Monday and puts temporary curbs on Iran's nuclear activities in exchange for modest sanctions relief.

Inspectors from the U.N. nuclear watchdog arrived in Tehran Saturday in readiness to oversee implementation of a landmark deal that puts temporary curbs on Iran's nuclear program, state media reported.

The team is led by the head of the International Atomic Energy Agency's Iran task force, Massimo Aparo, and will hold talks with Iranian nuclear officials, the official IRNA news agency said.

Iran denounced Friday as "one sided" a text released by the United States summarizing the implementation of the nuclear deal Tehran struck with world powers.

"The White House statement is a unilateral and one-sided interpretation of the unofficial agreements between Iran and P5+1" major powers, foreign ministry spokeswoman Marzieh Afkham said.

Iran summoned a UAE diplomat in Tehran over the "suspicious" death in custody of an Iranian in the Gulf state, media reported Friday.

"The foreign ministry is seriously following up on the case of Iranian citizen Ali Hosseini, who lost his life while he was detained by UAE security forces," Fars news agency quoted ministry spokeswoman Marzieh Afkham as saying.

Iranian Foreign Minister Mohammad Javad Zarif has said there is "good coordination" between Syria and its main allies, Moscow and Tehran, ahead of next week's planned peace conference, media reported Friday.

His comments came as the three countries' foreign ministers huddled in Moscow Thursday to devise a joint stance that would ease the pressure on President Bashar Assad to step down when the talks open in Switzerland after months of delays.

U.N. nuclear experts are to inspect Iran's Gachin uranium mine later this month for the first time in almost nine years, its Atomic Energy Organization said on Friday.

"The inspectors of the International Atomic Energy Agency will travel to Tehran on January 29 to visit Gachin mine," AEO spokesman Behrouz Kamalvandi told Iran's official IRNA news agency.