BEIRUT - The international envoy seeking to end Syria's civil war warned Sunday that the failure of the government and the rebels to pursue a political solution could lead to the "full collapse of the Syrian state" and threaten the world's security.

Lakhdar Brahimi, who represents the United Nations and the Arab League, said that as many as 100,000 people could be killed in the next year as Syria moves toward "Somalization" and rule by warlords.

Brahimi has reported little progress in his mission to push forward a peace plan for Syria first presented in June at an international conference in Geneva. The proposal calls for an open-ended cease-fire and the formation of a transitional government to run the country until new elections can be held and a new constitution drafted.

But so far, neither the regime of President Bashar al-Assad nor the scores of rebels groups fighting his forces across the country have shown any interest in negotiations.

The rebels' political leadership has called Assad's departure a prerequisite for any political solution, and it is unlikely that the opposition's National Coalition could even stop rebels on the ground from continuing to fight.

Likewise, it is doubtful that top members of Assad's regime will voluntarily give up power.

The Syrian government has remained officially mum on Brahimi's plan, which he has pushed in the past week in meetings with Assad in Damascus, with top Russian officials in Moscow and on Sunday with the head of the Arab League in Cairo.

Speaking alongside Nabil Elaraby on Sunday, he estimated that 100,000 people could be killed if the 21-month conflict continues for another year.

"Peace and security in the world will be threatened directly from Syria if there is no solution within the next few months," he said. "The alternatives are a political solution or the full collapse of the Syrian state."

Since meeting Assad early last week, Brahimi has given no indication how his plan was received. When asked Sunday if there is any willingness among the opposition to enter a political process, Brahimi said, "No, there isn't. This is the problem."

Syria's crisis began in March 2011 with political protests against Assad. The conflict has since evolved into a civil war. Anti-regime activists say more than 45,000 people have been killed. The Syrian government does not give death tolls for the conflict and says the rebels are terrorists backed by foreign powers who seek to destroy the country.