US airstrike kills several al-Qaeda militants in Syria

Several al-Qaeda militants were killed in a US air raid against the group's Syrian affiliate, al-Nusra Front, the Pentagon said Wednesday.

"I can confirm that the US struck a vehicle killing several al-Qaeda militants," said spokesman Matthew Allen. "The results of this strike are still being assessed."

A separate US air raid on Sunday killed Abu Firas al-Suri, al-Nusra's spokesman along with his son and 20 other militants in the northern Syrian town of Kafar Jales.

The latest strike was carried out in northwestern Syria, according to a Defense department official who asked not to be named.

The Washington Post reported the latest raid took place late on Tuesday.

US strikes on the al-Nusra Front in Syria have not been very frequent with the majority of airstrikes targeting the Islamic State group.

On Wednesday, a drone strike near IS's de facto Syrian capital Raqqa killed Tunisian commander Abu al-Haija, according to the Syrian Observatory for Human Rights, the latest in a series of blows to the jihadis in recent weeks.

Fifteen IS commanders accused of revealing his position have since been executed by the jihadis, and the fate of another 20 men accused of collaborating with the US-led coalition remains unknown.

"This is the highest number of executions of security officials by IS," said Rami Abdel Rahman, the SOHR director whose Britain-based group has a wide network of contacts across Syria.

News of the strikes came as talks in Geneva aimed at ending the conflict loomed on April 11.

Syrian peace talks which fail to address the question of President Bashar al-Assad's fate are "doomed to failure", a spokesman for the main opposition grouping involved in negotiations said.

Riad Naasan Agha, of the Riyadh-based High Negotiations Committee, said that the talks which are set to resume must focus on the future of the Syrian leader.

"If negotiations did not address the fate of Assad, it would be a waste of time and doomed to failure," he said late Tuesday at a forum hosted by Al-Jazeera in Qatar.

The UN has said the upcoming round of talks will focus on plans for a political transition to lead Syria out of five years of brutal civil war.

Agencies contributed to this report