Syria’s opposition took the country’s seat for the first time at an Arab summit Tuesday in a diplomatic triumph marred by divisions in the ranks of the Western-backed alliance.

The opposition’s rise to representation of Syria at the summit in Qatar, a key backer of President Bashar al-Assad’s foes, showed the extent of the Syrian government’s isolation two years into a civil war that the United Nations says has killed an estimated 70,000 people.

In Damascus, the government denounced the Arab League’s decision, portraying it as a selling-
out of Arab identity to please Israel and the United States.

In a further show of solidarity with anti-Assad forces, the Arab League endorsed the “right of each state” to provide the Syrian people and the Free Syrian Army with “all necessary means to . . . defend themselves, including military means.”

It was unclear whether the statement would open new weapons channels to fighters. But it was a symbolic slap against the U.S. and European allies that have resisted full-scale military aid to the rebels.

The opposition delegation led by Mouaz al-Khatib, the former president of the main opposition alliance, the Western-backed Syrian Opposition Coalition, took Syria’s assigned seats at the invitation of Qatar’s emir, Sheik Hamad Bin Khalifa al-Thani, while other delegates applauded. Hamad said the alliance deserved to represent Syria “because of the popular legitimacy they have won at home and the broad support they won abroad.”

But the diplomatic achievement could not conceal the disarray within the opposition’s top ranks.

Besides Khatib, the Syrian delegation included Ghassan Hitto, recently elected prime minister of a planned interim government to administer rebel-held areas in Syria, and two prominent opposition figures, George Sabra and Suheir Atassi.

Khatib announced his resignation Sunday because of what he described as restrictions on his work and frustration with the level of international aid for the opposition. The coalition rejected the resignation, and Khatib said he would discuss the issue later and represent the opposition at the Qatar summit “in the name of the Syrian people.”

Fighting, meanwhile, raged on in Syria. Rebels barraged Damascus with mortar shells that killed at least three people and wounded dozens in one of the most intensive attacks on the seat of Assad’s power. Also Tuesday, anti-regime activists said Syrian troops had seized control of Baba Amr, in the central city of Homs, a neighborhood considered a symbol of opposition to Assad.

— Associated Press

Bassem Mroue in Beirut contributed to this report.