TRIPOLI (AFP) - Libyan militant group Ansar al-Sharia denied on Tuesday that the Al-Qaeda-linked mastermind of a deadly 2013 siege at an Algerian gas plant had been killed in a United States air strike.

The group named seven people it said were killed in the US strike in eastern Libya but Mokhtar Belmokhtar, who Washington has said was the target, was not among them.

"No other person was killed," the group said in a statement.

The Pentagon had itself been non-committal about whether the strike by two F-15 Strike Eagle fighter jets armed with 500-pound bombs had succeeded in killing its target, who has been reported dead several times in the past.

US Air Force Secretary Deborah Lee James said: "The actual impact of that raid is still being assessed."

Belmokhtar, nicknamed variously as "The Uncatchable", "Mr Marlboro" and "The One-Eyed", is leader of the North African Al-Murabitoun militant group and a former chief of Al-Qaeda in the Islamic Maghreb (AQIM).

He allegedly masterminded the 2013 siege of an Algerian gas plant in which 38 hostages, mostly Westerners, were killed.

He was previously thought to have been killed in Mali, but security sources said last year he had moved to Libya.

Libya's LANA news agency cited a government official as saying the strikes targeted a farm south of Ajdabiya, some 160 km west of second city Benghazi, as Belmokhtar met leaders of other extremist groups including Ansar al-Sharia.

In its statement, Ansar al-Sharia, which is itself listed by Washington as a "terrorist" organisation, did not specify whether Belmokhtar had been at the meeting.