BEIRUT -- Several Syrian rebel groups, including a powerful al-Qaida-linked faction, said Wednesday they reject the authority of the Western-backed opposition coalition, as U.N. inspectors returned to the country to continue their probe into chemical weapons attacks.
In a joint statement, 13 rebel groups led by the al-Qaida-linked Nusra Front slammed the Turkey-based Syrian National Coalition, saying it no longer represents their interests.
The statement reflects the lack of unity between the political opposition, based in exile, and the disparate rebel groups fighting President Bashar Assad's regime in Syria's civil war, which has killed over 100,000 people so far. It also highlights the growing irrelevance of the Coalition and its military arm headed by Gen. Salim Idris, who heads the Supreme Military Council supported by the West, amid increasing radicalization on the ground in Syria.
The rebel groups' statement called on all those trying to topple Assad's government to unite under a "clear Islamic framework" -- an apparent reference to the al-Qaida faction's aspirations to create an Islamic state in Syria.
It said the rebels do "not recognize" any future government formed outside Syria, insisting that forces fighting on the ground should be represented by "those who suffered and took part in the sacrifices."
But the rebels themselves are also deeply divided, with many groups blaming jihadis and al-Qaida militants in their ranks for the West's reluctance to intervene militarily in Syria or give them the advanced weapons they need. There is also growing concern that the dominant role the extremists are playing is discrediting the rebellion.
Yet the jihadis, including members of the Islamic State of Iraq and the Levant, an al-Qaida offshoot, have been some of the most effective forces on the battlefield, fighting alongside the Western-backed Free Syrian Army to capture military facilities, strategic installations and key neighborhoods in cities such as Aleppo and Homs.
Meanwhile, a team of U.N. chemical weapons inspectors arrived in Damascus on Wednesday to continue investigating what officials from the world organization have described as "pending credible allegations" of the use of chemical weapons in Syria's civil war.
The visit of the six-member team, led by Swedish expert Ake Sellstrom, follows a report by the inspectors after their previous trip in September, which said nerve agent sarin was used in an Aug. 21, attack near the capital, Damascus.
The U.S. and its allies say Assad's regime was behind the attack, and Washington said it killed 1,400 people. Syrian activist groups gave significantly lower death tolls, but still in the hundreds.
Damascus blames the rebels for the attack, and Russia, a close ally of Assad, said the U.N. report did not provide enough evidence to blame the Syrian government. It has also demanded that U.N. inspectors probe other attacks that allegedly included chemical agents.
The United States and Russia brokered an agreement for Syria to give up its chemical weapons but U.N. diplomats say they are at odds on details of a Security Council resolution spelling out how it should be done and the possible consequences if Syria doesn't comply.
In a speech at the U.N. on Tuesday, President Barack Obama challenged the Security Council to hold Syria accountable if it fails to live up to its pledges.
"If we cannot agree even on this," Obama said, "then it will show that the United Nations is incapable of enforcing the most basic of international laws."
A statement by the U.N. on Tuesday said the inspectors will use their new visit to gather evidence from the alleged chemical weapons attack on March 19 on the village of Khan al Assal outside the city of Aleppo, which was captured by the rebels in July.
Wednesday's rebel announcement, carried by the Britain-based Syrian Observatory for Human Rights, came almost two weeks after the SNC, the main Western-backed opposition coalition, in Turkey elected Ahmad Saleh Touma as the opposition's interim prime minister.
Syrian rebels have been deeply divided and clashes between rival groups over the past months left hundreds of people dead, mostly in northern and eastern Syria. Al-Qaida gunmen have been on the offensive against members of the more mainstream Free Syrian Army, though some of the groups that signed on to Wednesday's statement also belong to the FSA umbrella.
Syria's conflict has taken on increasingly sectarian tones in the past year, pitting predominantly Sunni Muslim rebels against members of Assad's minority Alawite sect, an offshoot of Shiite Islam.