GENEVA — Kofi Annan said Thursday he will step down from his high-profile role as special envoy for Syria at the end of the month, delivering blistering criticism of world powers' failure to unite over the country's escalating violence.

At an impromptu press conference, Annan said he accepted the role when it seemed the international community led by the U.N. Security Council could help end the violence, enforce a cease-fire and bring about a political transition.

But the former U.N. secretary-general told reporters he cannot go on when the 15-nation council provides no backing for his role, particularly because of the standoff between its five veto-wielding members: Russia and China on one side, the United States, Britain and France on the other.

Annan has served as the U.N.-Arab League envoy to Syria since February. He came up with a six-point peace plan to resolve the crisis in the Arab state, including a cease-fire that was supposed to take effect in mid-April.

But, despite the presence of hundreds of U.N. observers on the ground, the cease-fire never took hold and the violence in Syria has spread into a civil war.

Rights activists say that more than 19,000 people have died since the popular uprising against Syrian President Bashar Assad began in March 2011.

"When the Syrian people desperately need action, there continues to be finger pointing and name calling in the Security Council," Annan told reporters in Geneva. "It is impossible for me or anyone to compel the Syrian government and also the opposition to take the steps to bring about the political process."

"As an envoy, I can't want peace more than the protagonists, more than Security council or the international community, for that matter," he added.

Annan said the failed six-point plan commonly referred to as the Annan plan is actually the Security Council's, since it was endorsed by them.

He did not rule out the idea of a successor being appointed by the current U.N. secretary-general, Ban Ki-moon, since "the world is full of crazy people like me, so don't be surprised if someone else decides to take it on."

Ban said in a statement he accepted the resignation with deep regret, and is discussing possible successors with the Arab League.

"I remain convinced that yet more bloodshed is not the answer; each day of it will only make the solution more difficult while bringing deeper suffering to the country and greater peril to the region," Ban said.

"The hand extended to turn away from violence in favor of dialogue and diplomacy — as spelled out in the six-point plan — has not been not taken even though it still remains the best hope for the people of Syria."

Russia's U.N. envoy Vitaly Churkin said that Moscow also regrets Annan's decision to step down, according to the RIA Novosti news agency. But Churkin said he was encouraged by Ban's search for a replacement.