BEIRUT -- The military commander of al-Qaida's Syrian affiliate was killed Thursday in an explosion targeting a meeting of senior militants in northern Syria which also killed and wounded a number of other fighters.

State-run news agency SANA said Abu Hommam al-Shami was killed in a military operation carried out by the Syrian army that targeted a Nusra Front meeting in the village of Habeet, in the northern Idlib province.

It did not elaborate, but the report suggested he was killed in an airstrike.

The Britain-based Syrian Observatory for Human Rights confirmed that a number of prominent leaders, including Abu Hommam, were killed when a Nusra Front leadership meeting was targeted.

It said it was not clear whether the meeting was targeted by a U.S.-led coalition airstrike or a Syrian army strike.

The fate of the group's overall leader, Abu Mohammad al-Golani, was not clear, it said, although there were reports that he had been in the area.

The reports could not be independently verified.

The Syrian government, which insists it is fighting terrorists in Syria, has an interest in taking out Nusra and Islamic State leaders to prove it is fighting a shared enemy of the West. It has in the past claimed to have killed al-Golani, but the reports were later refuted.

The U.S. has been carrying out airstrikes against the Islamic State group in Syria, a rival of the Nusra Front, and has on several occasions struck a cell within Nusra that U.S. officials say was plotting attacks against the West.

The Nusra Front controls large parts of northern Syria and Idlib province in particular, and has seized territory from other more moderate rebels fighting to topple President Bashar Assad. Most recently, it has clashed with the U.S.-backed Hazm group, which later dissolved itself.

Earlier Thursday, Syrian government helicopter gunships bombed the northern city of Aleppo, killing at least 18 people and wounding dozens, activists said.

The bombings came as Syrian President Bashar Assad vehemently denied in an interview with Portuguese state television that his military drops crude explosives known as barrels bombs on civilians.

"You are talking about massive propaganda," Assad said in the interview.

The aerial attack on a rebel-held neighbourhood was in apparent reprisal for an attack the day before by opposition fighters against a building used by the government's state intelligence services.

Syrian aircraft have dropped hundreds of barrel bombs over the course of the civil war, killing thousands of civilians and causing widespread destruction. The crude tactic -- which often involves hurling explosives-filled canisters from helicopters -- has been widely criticized by human rights groups because the bombs are not precise.

An Aleppo-based activist who goes by the name Abu Raed said one barrel bomb struck a shop that sells gasoline and diesel fuel. He said a fire broke out and that many bystanders were burned.

Abu Raed said the strike on the Qadi Askar neighbourhood killed at least 20 people, while the Britain-based Syrian Observatory for Human Rights put the number at 18 dead.

Syria's conflict, which began in March 2011, has killed more than 220,000 people, a figure that was disputed by Assad in the interview as an exaggeration.