Soon after an airstrike by the US military in northern Syria against an al Qaeda target Thursday evening, the military denied targeting a mosque deliberately, where at least 42 people were killed, reports said.
The jets struck as the mosque was full of worshippers at evening prayer on Thursday, said the Syrian Observatory for Human Rights, which monitors the country's civil war.
ISIS had at one point held the area around al-Jineh as part of its push into the northwestern part of Aleppo, but appears to have been expelled.
The U.S. Central Command based in Tampa, Florida, said separately that U.S. forces killed "several terrorists" in a strike at an al Qaeda meeting place in Idlib.
Civil defense official Yahya Javad said the attack also wounded dozens of others in the city's Al-Etarip area. A journalist for the monitoring project Airwars said that CENTCOM officials had confirmed the strike was carried out by USA forces.
That building was 40 to 50 feet from the mosque, but recent satellite imagery shows the mosque still is standing, the official said.
The U.S. has struck dozens of locations in the region, where an al-Qaeda-linked alliance of rebel groups is now the ascendent force.
He said the USA was aware the mosque was next door and deliberately did not strike it.
Jihadi and militant websites said the group, which aims to encourage people to adhere to Islam by peaceful means, was holding a weekly meeting with about 250 people in attendance. But independent monitoring groups put the number at hundreds, and at times, thousands more.
The US has been bombing jihadists in war-torn Syria as part of an worldwide coalition since 2014, with hundreds of civilians unintentionally killed in the country and in neighbouring Iraq.
First responders and local activists said at least 35 people were killed.