PARIS: Russia and Iran have a key role in the efforts to end the bloodshed in Syria, international envoy Kofi Annan said Sunday, while adding that so far his work to bring peace has failed.

The U.N.-Arab League envoy told France's Le Monde daily that the 16-month carnage in Syria showed no sign of ending and there was no guarantee that his mediation would bear fruit.

"It's been three months since I have been involved," he said in an interview published in French.

"Great efforts have been made to try and resolve this situation in a peaceful manner with a political solution," he said. "Evidently, we have not succeeded. And maybe there is no guarantee that we will succeed."

The Annan plan, which insists on a cessation of violence by all sides, has made little headway, and activists say more than 17,000 people have now died since the uprising began in March last year.

U.N. chief Ban Ki-moon called on Friday for scaling down an observer mission in Syria to refocus on political efforts to end the conflict.

Former U.N. chief Annan highlighted the importance of Russia -- a Damascus ally that has blocked global action against President Bashar Assad's regime -- while also stressing that Iran should be involved in discussions.

"Russia wields influence but I am not sure that the events will be determined by Russia alone.... Iran is an actor. It has to be part of the solution. It has influence and we cannot ignore it."

Annan also expressed irritation that while Russia and Iran were mentioned by some as stumbling blocks to peace, "little is said about other countries which send arms, money, and have a presence on the ground."

Iranian President Mahmoud Ahmadinejad has accused the United States and its allies of opposing Assad's regime with the goal of dominating the Middle East and propping up Israel.

"The main enemies... are trying to revive their domination of the region and to save the occupying regime from destruction," the Iranian leader said ahead of a Friends of Syria meeting in Paris Friday grouping some 100 countries.

"The Americans are seeking only their interests, and it is the right of the people of the region, including the great Syrian people, to freely decide their own fate and others should not impose their demands on them," he said.

Annan oversaw a meeting in Geneva last weekend that agreed a transition plan for Syria whose language skirted around the issue dividing Western powers from Russia and China: whether or not Assad should have a role in a new unity government.

Russia and China say it is up to the Syrian people to decide Assad's fate. The two countries have blocked action in the U.N. Security Council against Assad's government.

But the United States insists Assad should go as part of a solution.

Washington also objected to Iran taking part in the Geneva meeting, resulting in Tehran being excluded.

Iran is Assad's chief regional ally, supplying him with humanitarian and financial aid.

Some Iranian and U.S. reports say Iranian military personnel were in Syria helping in the crackdown against opposition groups, though Tehran officially denies that.