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 anew constitution drafted.

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

“The situation is bad and it’s getting worse,” Brahimi said in Cairo. “I can’t see anything other than these two paths: Either there will be a political solution that will meet the ambitions and legitimate rights of the Syrian people, or Syria will turn into hell.”

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, experts say.

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 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.

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 Syria 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.

The Syrian conflict has split world powers, with the United States, Turkey and many European and Arab states calling for Assad to stand down, while Russia, China and Iran have stood by the regime and criticized calls for Assad’s ouster.

On Sunday, Turkish Prime Minister Recep Tayyip Erdogan visited Syrian refugees along Turkey’s southern border, where he was joined by Mouaz al-Khatib, head of Syria’s National Coalition.

Erdogan called for Assad to step down and said Syria is experiencing “a holy birth.”

“That holy birth is the coming to power of the will of the people,” he said as refugees chanted his name.

Meanwhile, activists reported violence across Syria.

The Syrian army killed 143 people Saturday, the opposition Local Coordination Committees said in an e-mailed statement. Fifty unidentified beheaded corpses with signs of abuse were recovered behind Tishreen Military Hospital in Damascus, the group said.

On Sunday, rebels in the north clashed with government troops near military bases in the provinces of Idlib and Aleppo and seized an oil pumping station in al-Raqqa.

The station receives crude oil from the nearby province of Hassakha and pumps it to one of Syria’s two oil refineries in Homs, said Rami Abdul-Rahman, who heads the Syrian Observatory for Human Rights.

The Observatory also said rebels stormed a government air base in the area of Tel Hassir south of Aleppo, while government fighter jets launched deadly airstrikes near Aleppo, Hama and in a number of rebellious Damascus suburbs.

Activists also reported two car bombs in the Yarmouk district of Damascus, where most residents are Palestinian refugees.

Meanwhile, Russian news agencies said the navy was sending another ship to the Syrian port of Tartus, where Russia has a naval base.

ITAR-Tass and Interfaxnews agency cited an unidentified official in the Russian military general staff as saying the Novocherkassk, a large landing ship, has set sail from the Black Sea port of Novorossiisk for the Syrian port of Tartus.

The reports gave no information on the ship’s intent. But Russian diplomats have said Moscow is preparing a plan to evacuate thousands of Russians from Syria if necessary. The Defense Ministry announced two weeks ago that several ships were being dispatched to the Mediterranean.

In other developments, Jordan said it is prepared to deal with any potential chemical weapon threat posed by the ongoing violence in neighboring Syria, but said it will not enter “any alliance” to protect itself.

Jordan, the U.S. and others have expressed concern that Assad could use chemical weapons in a last-ditch effort to save his regime.

Information Minister Sameeh Maaytah did not provide details on Jordan’s capabilities to thwart a chemical attack in remarks carried by the official Petra news agency Sunday. But other Jordanian officials have said U.S. and British military experts have provided training in protecting civilians in case of a chemical attack on Jordanian territory.

Information for this article was contributed by Bassem Mroue, Suzan Fraser and Sarah El Deeb of The Associated Press and by Henry Meyer, Scott Rose, Brendan McGarry, Zaid Sabah Abd Alhamid, Alaa Shahine, Dana El Baltaji and Glen Carey of Bloomberg News.

Front Section, Pages 1 on 12/31/2012