Beirut: The military chief and several top commanders of the Al Qaida-affiliated Al Nusra Front have been reported killed in northwestern Syria, where the militia has been making major gains in recent months.

Syrian state media, a monitoring group and a local activist reported that Abu Hammam Al Shami had been killed but information on the circumstances of his death was contradictory.

Official Al Nusra sources did not announce the death of the militant, who is believed to have fought with Al Qaida in Afghanistan.

“Shami... was killed with a number of other leaders during a special operation by the army” in Idlib province, Syrian state news agency SANA reported, without specifying a date.

Rami Abdul Rahman, the head of the Syrian Observatory for Human Rights monitoring group, also said the commander had been killed but that the circumstances of his death were unclear.

“Shami died of injuries on Thursday, but it is not clear when he sustained them,” Abdul Rahman said.

He said Shami may have been one of five Al Nusra leaders wounded in an air strike on Idlib province on February 27 by the US-led coalition attacking militants in Syria.

An official Al Nusra statement that day named two commanders killed in that strike, but did not mention Shami.

Local Syrian activist Ebrahim Al Idlibi said Shami had been killed in that raid but that Al Nusra had not published his name due to the “sensitivity” of the information.

Reports of Shami’s death came as the Al Al Qaida affiliate consolidates gains in northern Syria.

Already the most powerful military force in Idlib province, Al Nusra dealt a major blow to one of its rivals — the western-backed Hazm movement — at the weekend when it seized Hazm’s base in Aleppo province.

Al Nusra also claimed to have led a spectacular assault against a regime intelligence headquarters in Aleppo city on Wednesday, blowing up a tunnel near the building before storming the surrounding area.

Attacks on the group’s leadership are “an indication of the rising strength and influence of Al Nusra on the ground in Syria in recent months,” said Lina Khatib, director of the Carnegie Middle East Centre think tank.

“Because it operates in a decentralised manner, not top down, the loss of a leader is something that Al Nusra can recover from with minimal damage,” she said.

But Idlibi, the local activist, disagreed.

“It’s a definite hit to the morale of Al Nusra’s supporters,” he said.

He said there were rumours of serious internal disputes within Al Nusra’s ranks regarding an apparent Qatar-led proposal for Al Nusra to split off from Al Qaida.

“They want to turn it into something like the Taliban - into a political movement,” he said.

Idlibi said Al Nusra political chief Abu Mohammad Al Jolani is in favour of the split, while Shami was against it.

Al Nusra has emerged as the most powerful militant group in northwestern Syria and, as well as fighting President Bashar Al Assad’s regime, has clashed with moderate rebels and its rival Daesh.

Shami is reported to have travelled to Afghanistan in the late 1990s and was eventually put in charge of Syrian militants there. He later spent five years in prison in Lebanon, before travelling to Syria and joining Al Nusra.