Warplanes struck a mosque in the rebel-held village of Al-Jina, southwest of Atarib near Aleppo in Syria, killing at least 42 people and wounding dozens, the Syrian Observatory for Human Rights, a Britain-based war monitor, said on Thursday.

“The raids by unidentified warplanes targeted a mosque in Aleppo province during evening prayers, killing 42 people, most of them civilians,” said the head of the Britain-based Observatory, Rami Abdel Rahman.

“More than 100 people were wounded,” he said, adding that many were still trapped under the collapsed mosque in the village of Al-Jineh, just over 30 kilometres (20 miles) west of Aleppo.

Rescue workers struggled to pull survivors from rubble, and dozens of residents were still unaccounted for, the Observatory said.

The jets struck the mosque on Thursday when it was full of worshippers at evening prayers, said the Observatory, which monitors the Syrian war via a network of contacts across the country.

Footage published by Halab Today, an online media group focused on news in Aleppo, showed piles of rubble where the mosque stood.

The village is located in one of the main rebel-held parts of Syria, the northwest region that includes Idlib province and the western parts of Aleppo province, and its population has been swollen by refugees, UN agencies said.

The Syrian and Russian military have carried out many air strikes in Idlib and Aleppo provinces during the war. The US has also carried out strikes there in recent months, targeting a militant rebel group that until last year was a formal affiliate of al-Qaeda.

Some activists allege that the US carried out the strike, but no country has officially taken credit for it at this point.

Rebels in northwest Syria fighting to oust President Bashar al-Assad also include groups supported by Turkey, the US and Gulf monarchies.

More than 320,000 people have been killed in Syria since the conflict began six years ago with anti-government protests.