A Libyan affiliate of the extremist Islamic State group claimed responsibility Wednesday for an attack on a Tripoli luxury hotel that killed 10 people, including an American and four Europeans.

The group, calling itself "Islamic State in Tripoli Province," said it launched the attack Tuesday to avenge the death of Abu Anas al-Libi, who was snatched off a Tripoli street by U.S. special forces in 2013 and died in U.S. custody earlier this month due to complications from liver surgery. Al-Libi had been indicted in U.S. federal court over his alleged role in the 1998 Al Qaeda bombings of U.S. embassies in Kenya and Tanzania.

The group identified the attackers as Abu Ibrahim al-Tunsi and Abu Suleiman al-Sudani, noms de guerre that suggest the attackers were Tunisian and Sudanese. The claim of responsibility was dated Tuesday but first appeared on jihadi forums Wednesday.

"The operation is not the last one on the lands of Tripoli... Let the enemies of God, the crusaders and their allies await what would harm them," the message read.

The affiliate previously claimed responsibility for an attack on the Algerian Embassy that wounded three guards. It also previously posted pictures of fighters touring markets and distributing pamphlets. Wednesday's posting matched previous messages posted on Twitter and social media, but it was not immediately possible to confirm the claim.

Since the 2011 uprising that ousted longtime dictator Muammar Qaddafi the country has been awash in armed militias, including several Islamic extremist groups. A group of Islamist militias control Tripoli, and the internationally recognized government convenes in the far east of the vast, oil-rich country.

In addition to the foreigners, five guards were killed in the attack Tuesday on the seaside Corinthia Hotel. Two attackers were killed following an hourslong standoff that included a car bombing.

A senior U.S. State Department official confirmed that an American citizen was among those killed. Cliff Taylor, the CEO of a Virginia security company, Crucible LLC, identified the slain American as David Berry, a contractor with his company.

The online message said that those killed were American, French, South Korean and Filipino. Earlier, Essam al-Naasa, a spokesman for a Tripoli security agency, said the dead included an American, a French citizen and three others from the former Soviet Union.