BEIRUT - Two suicide bombers killed a senior al-Qaida operative Sunday, blowing themselves up inside the militant leader’s compound in the northern Syrian city of Aleppo, rebels and activists said.

The killing of Abu Khaled al-Suri, who rebels said was serving as al-Qaida chief Ayman al-Zawahri’s representative in Syria, comes amid bloody rebel infighting between an al-Qaida-breakaway group known as the Islamic State of Iraq and the Levant, and an array of ultraconservative and more moderate opposition fighters.

There was no immediate claim of responsibility for Sunday’s assassination, but rebels quickly accused the Islamic State of Iraq and the Levant. Al-Suri had been critical of the group, reportedly blaming it for the conflict among rebels that has killed thousands of people across northern Syria since it began in early January.

If an Islamic State of Iraq and the Levant role in al-Suri’s death is confirmed, it could further complicate efforts to resolve the infighting, which has undermined rebel efforts to oust President Bashar Assad in Syria’s nearly three-yearlong civil war. Since the rebel-on-rebel clashes began, government forces have chipped away at opposition-held areas, including around Aleppo.

A native Syrian with long-standing ties to al-Qaida, al-Suri was a co-founder of Ahrar al-Sham, a prominent, hardline rebel group in Syria that is part of a powerful alliance of seven groups known as the Islamic Front.

Akram al-Halabi, a spokesman for the Islamic Front, described al-Suri as “a big figure in global jihad,” and said he was appointed by al-Zawahri last year to mediate a dispute between the two al-Qaida affiliates in Syria: the Islamic State and the Nusra Front.

Speaking via Skype, al-Halabi said al-Suri had criticized the Islamic State of Iraq and the Levant for its antagonistic approach toward other rebel factions. He said rebels think the Islamic State of Iraq and the Levant, which al-Qaida publicly disowned earlier this month, was behind Sunday’s bombing.

“The first fingers of blame point to the State,” al-Halabi said. “Unfortunately, this isgoing to make the infighting worse.”

He did not provide any evidence to support his assertion that the Islamic State of Iraq and the Levant had a hand in al-Suri’s killing.

The Britain-based Syrian Observatory for Human Rights said two others were also killed in the attack, which it attributed to the Islamic State of Iraq and the Levant. The Observatory obtains its information from a network of activists on the ground.

Al-Suri had long been on the radar of Western intelligence agencies. In 2002, Spanish officials described al-Suri, whose real name is Mohamed Bahaiah, as the courier between Afghanistan and Europe for the late terrorist leader Osama bin Laden.

Islamic extremists have emerged as a powerful force in Syria’s civil war. The rise to prominence of hard-line Islamic militants like al-Suri has sent jitters through Western capitals and dampened enthusiasm for the anti-Assad opposition.

Charles Lister, an analyst with the Brookings Doha Center, said al-Suri’s activities in Syria had been a source of concern for the U.S. and its allies.

“He is essentially a core al-Qaida veteran who almost certainly … had extensive, close relations with [Osama] bin Laden,” and other senior leaders, Lister said. “The fact that he had such a high position in Ahrar al-Sham, and confirmed it himself, his al-Qaida history - it made elements in the U.S. administration potentially consider Ahrar al-Sham as a terrorist organization.”

Syria’s uprising began with largely peaceful protests in March 2011 before turning into a civil war that has killed more than 140,000 people. The conflict has also forced 2.5 million to flee the country and left millions more in desperate needof aid.

On Saturday, the United Nations Security Council passed a resolution demanding immediate access everywhere in Syria for humanitarian aid. The resolution, which marked a rare instance of unity on the Security Council, doesn’t threaten sanctions, but it does express the council’s intention to take “further steps” if the resolution isn’t implemented

Syria’s Foreign Ministry on Sunday welcomed the resolution and voiced its readiness to cooperate but said the top priority must be respecting national sovereignty.

Damascus says the crisis in the country is caused by an international conspiracy against Syria.

Also Sunday, a car bomb exploded near a charity field hospital close to the Turkish border, wounding mostly medics and patients who had fled violence elsewhere in the country, activists and Turkish media said.

Turkish ambulance crews evacuated at least 11 of the wounded, including a 5-monthold baby, to Turkey, said Syrian activists of the Idlib News group.

Zidane Zenglow, a journalist working for the pan-Arab al-Arabiya network, said at least one person was killed in the blast - a young girl, his cousin. Information for this article was contributed by Maamoun Yousef, Ryan Lucas, Yasmine Saker and Suzan Fraser of The Associated Press.

Front Section, Pages 5 on 02/24/2014