A US military air strike in north-western Syria has killed more than 100 al-Qaeda militants at a training camp, the Pentagon says.

Spokesman Capt Jeff Davis said the camp in Idlib province had been in operation since 2013.

The attack involved a B-52 bomber and an undisclosed number of drones, officials said.

The strike on Thursday was the second major US military attack in the final hours of Barack Obama's presidency.

Less than 24 hours earlier, a combination of B-2 stealth bombers and drones killed up to 90 so-called Islamic State (IS) militants in two camps in a remote area of Libya, officials said.

Capt Davis said the Syria attack disrupted training operations "and discourages hard-line Islamist and Syrian opposition groups from joining or co-operating with al-Qaeda on the battlefield".

He said it capped a series of successful strikes against al-Qaeda recently.

"These strikes, conducted in quick succession, degrade al-Qaeda's capabilities, weaken their resolve, and cause confusion in their ranks," he said.