SINGAPORE - Former United Nations Secretary-General Kofi Annan said Wednesday that negotiation is the only possible way to find a solution to the Syrian crisis.

The only way out is to move the fighters from the military front to the negotiating table, and the differences within the UN Security Council need to be bridged, Annan said at a dialogue session at the Lee Kuan Yew School of Public Policy of the National University of Singapore.

He also said Iran should have a role in the solution, given its influence in Syria.

"I know some countries have difficulties with Iran, but you don't make peace with your friends, you make peace and reach out to the countries that can make a difference," he said.

Annan used to be an international mediator on Syria, where the five members of the UN Security Council have been divided over whether certain steps should be allowed to be taken against regime of Syrian President Bashar al-Assad.

Annan said China and Russia were hesitant to allow the Security Council to take certain steps in Syria's case, because they felt they had been "duped" into supporting intervention in Libya, where they had abstained from voting and enabled action to be taken that helped topple Muammar Gaddafi's regime.

"They were shocked by the way the mandate was transformed into regime change so quickly," he said.