Moscow, Jan 21 (IANS): The UN's decision to withdraw Iran's invitation to the Geneva II conference on the Syrian crisis was a mistake, the Russian foreign minister said Tuesday.

"The interests of the cause essentially require the representation of Iran, like all the other countries of the region," Russian Foreign Minister Sergei Lavrov said in a press conference.

"In this case, we are speaking about a one-day event Jan 22, to which some 40 foreign ministers from different states, including the most remote regions, have been invited," Xinhua quoted Lavrov as saying.

Meanwhile, Iran said that it would not participate in the Geneva II conference because of the US's irrational insistence on setting conditions for it, Iran's Deputy Foreign Minister for Arab and African Affairs Hossein Amirabdollahian said.

Amirabdollahian said despite Iran's readiness for unconditional participation in the conference, which is aimed at finding a political solution to the Syrian crisis, the US insisted on setting preconditions for the country, the official IRNA news agency reported.

Russia's Lavrov also cited US Secretary of State John Kerry, who earlier said Iran must play an important role in finding a solution to settle the Syrian crisis.

A turmoil erupted after Iran was invited Sunday to the meeting in Montreux, Switzerland, scheduled for Jan 22. The main Syrian opposition group, which earlier decided to participate, threatened to pull out of the conference shortly after Iran was invited to participate in the meeting.

UN Secretary General Ban Ki-moon later said the meet would proceed without Iran despite his earlier invitation to the country, saying Tehran had failed to confirm its adherence to the Geneva I communique.

For months, UN, US and Russian diplomats have struggled to persuade both the Syrian regime and rebels opposed to it to attend the conference.

The Russian foreign minister said Iran's absence at the Geneva II conference would not facilitate defeating terrorism in the Muslim world, nor provide unity of the Muslim world.

"Terrorism is a threat to us all, Muslims including," Lavrov said, adding Moscow had consistently warned of the danger of a split in the Muslim world, which would bring about catastrophic consequences.

Lavrov said Russia was trying its best to "promote political settlement" of the Syrian crisis.

"We are satisfied with the fact that reasonable approaches based on the logic of peace and basic principles of international law prevailed," he said, adding Russia was against unilateral actions, including attempts to use force bypassing the UN Charter.