Syrian opposition chief Ahmed Moaz al-Khatib said Tuesday he had asked that NATO's Patriot missile system be extended to protect rebel zones inside the war-torn country, as he took up Syria's seat in the Arab League for the first time.

Launching into a fiery speech after leading a delegation into a Doha summit to thunderous applause from Arab leaders, Khatib also demanded that the opposition be allowed to represent Syria at the United Nations.

"I have asked (US Secretary of State) Mr John Kerry during our meeting to provide Patriot (missile protection) that encompasses northern Syria, and he has promised to look into the matter," Khatib told the summit.

"We are still awaiting a decision from NATO on this matter."

NATO's sole involvement in Syria's brutal civil war to date has been to position Patriot missile batteries along the Turkish border in order to prevent any air or missile launches from the Syrian side.

Khatib, who threw the opposition into disarray by announcing his resignation on Sunday, made it clear that he was still firmly at the helm of the Syrian National Coalition, the main Syrian opposition umbrella grouping.

Taking the seat reserved for the delegation head at the invitation of Qatar Emir Sheikh Hamad bin Khalifa Al-Thani, Khatib was flanked by other senior opposition figures including prime minister Ghassan Hitto.

There had been confusion over whether the delegation would be headed by Khatib or by Hitto, in the wake of the Coalition leader's resignation.

Khatib however was the one who did the speaking, after the opposition flag was raised in place of the official Syrian bunting.

"We demand ... all forms of support from our friends and brothers including our full right for self-defence and the seat of Syria at the United Nations and at other international organisations," he told the summit.

He called for a "freezing of the funds of the regime which it had stolen from our people," estimated by the opposition at around two billion dollars.

He also stressed that the Syrian people alone would determine the future of their country.

"They ask who will rule Syria. The people of Syria will decide, not any other state in this world," Khatib said, possibly alluding to accusations by Damascus that the rebels are implementing Qatari and Saudi agendas.

"The Syrian people's decisions are based on its interests. It rejects any foreign mandates," he said.

In his speech, Arab League chief Nabil al-Arabi described the Coalition as "the sole and legitimate representative of the Syrian people after it succeeded in forming an interim government."

The seat has been empty since the Arab League suspended Syria's membership in November 2011 after Damascus rejected an Arab proposal to end violence against protesters and instead pressed a bloody crackdown on dissent.

The Arab Spring-inspired protests morphed into an armed rebellion against Assad's regime and later into a civil war in which more than 70,000 people have been killed so far, according to UN figures.

Damascus reacted furiously to the decision of the 22-member grouping.

"Shame on you, Arab brothers," wrote Tishreen state-owned daily, branding the Arab League decision as a "theft".

"This theft that the sheikhdom of Qatar and other collaborator, treacherous, backward Arab regimes have committed by handing the Doha-sponsored Coalition the Syrian state's membership... is a legal, political and moral crime," it said.

Khatib in his address made no mention of his resignation, but ahead of the summit he had said it would be dealt with after the meeting is over.

Coalition spokesman Khaled al-Saleh said that Khatib's resignation "has not been accepted" and that "most members of the coalition want him to continue to lead" at this time.

Khatib in his speech on Tuesday pointedly expressed his confidence in Hitto.

"We trust him. The general assembly of the coalition awaits his programme to debate it," he said.