The new U.N. special envoy for Syria says his mission to find a peaceful resolution of the Syrian conflict will be difficult unless the U.N. Security Council supports him by speaking “with a unified voice.”

Former Algerian diplomat Lakhdar Brahimi was speaking in an interview with The Associated Press published Sunday, two days after his appointment to the U.N. and Arab League's joint post.

Brahimi also said he has no specific ideas about how to achieve a consensus in the Security Council on Syria.

Russia and China have repeatedly blocked attempts by Western and Arab powers to pass Council resolutions threatening sanctions against Syrian President Bashar al-Assad for violently suppressing a 17-month rebellion against his autocratic rule. Moscow and Beijing insist the Council should not take sides in the Syrian conflict.

Syria's main exiled opposition group, the Syrian National Council, said Sunday it wants Brahimi to apologize to the Syrian people for saying it is too early for him to call on the Syrian president to step down.

Brahimi made the remark in an interview last week. He defended his comments Sunday, telling Arab TV network Al Jazeera that it is premature for him to comment on the content of his mission.

Before stepping down, Brahimi's predecessor Kofi Annan said Mr. Assad “must leave office.” Mr. Annan quit earlier this month, complaining that he could not fulfill his mission due to international divisions on Syria and escalating attacks by Syrian government and rebel forces.