"If we are going to have peace and stability in the Middle East, it is essential that Iran plays its natural role in the region," Annan, who also served as the UN/Arab League envoy to Syria for five months in 2012, told Reuters in an interview at the World Economic Forum in Davos on Friday.

Annan's successor as UN chief, Ban Ki-moon, issued and then withdrew an invitation to Iran to join the international peace talks on Syria in Switzerland.

A number of US-led Western and Arab nations co-sponsoring the Geneva II conference insisted that Iran could only participate if it accepted an imposed plan for a power transition in Syria, something Tehran has persistently rejected as an undemocratic and arbitrary plan, maintaining that it would only take part in the Geneva II talks without preconditions.

The Iranians have their own politicians who are not convinced this (rapprochement) is the way to go, Annan said, adding that Washington has its own figures who do not believe this is the way to go and are even talking about imposing fresh sanctions in the middle of the (nuclear) negotiations process.

"It would lead to a division between Europe and the US. I would urge my friends in Washington to think through this before they push ahead," he said. "They should give diplomacy, negotiation and peace a chance."

Syria has been gripped by a foreign-sponsored insurgency since 2011. According to reports, Western powers and their regional allies - especially Qatar, Saudi Arabia, and Turkey - are supporting the militants operating inside the country.

According to the United Nations, more than 100,000 people have been killed and millions displaced due to the destructive and bloody turmoil.

NTJ/MB