DUBAI, United Arab Emirates -- To the outrage of Syria's embattled government, the opposition coalition leader formally took its vacant seat at an Arab League summit meeting on Tuesday and immediately requested broader recognition, including from the United Nations, as part of an effort to further ostracize President Bashar al-Assad.
The decision to grant the Arab League seat to the Syrian opposition coalition, recommended by the Arab League's foreign ministers at a meeting earlier this month, was considered a symbolic but important milestone in the two-year-old Syrian conflict. The Arab League suspended Syria's membership in November 2011 in reaction to Mr. Assad's repression of political protests, which have evolved into a civil war that has left 70,000 people dead and millions displaced.
"Syrian people alone should determine who rules the country," the leader of the opposition delegation, Moaz al-Khatib, said in a speech at the Arab League summit meeting in Doha, Qatar, after the host, Sheik Hamad bin Khalifa al-Thani, the emir of Qatar, formally invited him to take the seat as other ministers applauded. Mr. Khatib called the Arab League's decision "part of the restoration of legitimacy that the people of Syria have long been robbed of."
Even before Mr. Khatib took his seat, Mr. Assad's government reacted harshly in anticipation of such a move.
"Shame on you, Arab brothers," said the pro-Assad newspaper Tishreen in Damascus, according to a translation by Agence France-Presse. The newspaper denounced what it called "this theft that the sheikdom of Qatar and other collaborator, treacherous, backward Arab regimes have committed."
Mr. Khatib was accompanied to the summit meeting by other prominent opposition figures, including Ghassan Hitto, a naturalized American citizen who was elected as the coalition's interim prime minister last week. Images broadcast from the meeting showed the opposition's green and black flag with four red stars placed to Mr. Khatib's right, replacing the Syrian government's red, white and black flag with two green stars.
The moment of triumph for Mr. Khatib and Mr. Hitto overshadowed, for the moment, the fractiousness that has troubled the opposition coalition. Mr. Khatib announced his resignation a few days ago out of frustration at what he called insufficient help from foreign powers, although that decision did not appear to be final. The selection of Mr. Hitto was made in a sharply divided vote.
Using the Arab League as a new perch of legitimacy, Mr. Khatib said the opposition now wanted "the seat of Syria at the United Nations and at other international organizations."
Mr. Khatib also told the ministers that he had requested that NATO extend its Patriot missile-defense protections deployed in southern Turkey to include a section of rebel-held territory in northern Syria, where opposition forces remain vulnerable to Syrian Air Force attacks. But there was no indication that NATO would comply with such a request, which would amount to a partial no-fly zone imposed on Syrian airspace.
Turkey, a NATO member that supports the Syrian insurgency, had requested the Patriot defenses to deter the threat of Syrian airstrikes on its territory.
At the United Nations, Ban Ki-moon, the secretary-general, appointed Ake Sellstrom, a Swedish scientist, to lead an investigation into allegations that chemical weapons were used in Syria last week.
Mr. Sellstrom has previous experience in the region, having been the chief inspector of the United Nations team that worked to find and dismantle Iraq's chemical and biological weapons programs in the 1990s.
He returned to Iraq in 2002 to work with a different United Nations team that found no solid evidence that President Saddam Hussein had resurrected the program to build banned arms before the United States invaded in March 2003.
A dispute within the United Nations Security Council on the chemical weapons issue remains unresolved -- Russia wants investigators to examine only allegations by each side that the other used chemical weapons in Aleppo on March 19. Britain, France and the United States want other allegations of chemical weapons use in Damascus and Homs, made by the opposition against Mr. Assad's government, included in the investigation.
No timetable or formal mandate for the investigation team has been announced.
Also at the United Nations, the Security Council reviewed the deployment of the United Nations observer force in the Golan Heights, following the brief abduction of 21 Filipino soldiers by Syrian rebels earlier in March.
The unarmed force has been deployed since 1974 to monitor the cease-fire between Israel and Syria. When established, nobody envisioned a time when they would be caught in the middle, with a civil war in Syria bringing occasional exchanges of gunfire and artillery between the Syrian side and the Israelis sailing over the heads of the United Nations monitors.
Hervé Ladsous, the head of all United Nations peacekeeping operations, said that the force would adopt a more "static posture" along the roughly 50-mile disputed border, going out less on patrol.
Hala Droubi reported from Dubai, and Rick Gladstone from New York. Neil MacFarquhar contributed reporting from the United Nations.
This article originally appeared in The New York Times.