Washington: One American worker was killed at a natural gas complex in Algeria where Al Qaeda-linked militants held more than 130 foreign workers hostage, the US State Department said.
"We express our deepest condolences to his family and friends," Xinhua quoted State Department spokeswoman Victoria Nuland as saying in a statement.
The victim was identified as Frederick Buttaccio from Texas.
Nuland did not release further details.
US media reports said Buttaccio's remains had been recovered from the gas complex near In Amenas in the southern Algerian province of Illizi.
It remained unknown whether Buttaccio was the only American worker killed in the hostage crisis.
The militants said they wanted to avenge Algeria's support for French involvement in the conflict in neighbouring Mali.
At least 30 foreign workers were reportedly still unaccounted for as of Friday.
Algerian troops Thursday launched an air-and-ground raid on the gas complex in an attempt to rescue the hostages.
Algeria's official APS news agency said more than 670 hostages, including 573 Algerians and about 100 foreigners, were freed in the raid, which also left 12 hostages and 18 militants dead.
But the assault was criticised by some countries, including Japan and Britain, which complained they were not informed of the operation.
Speaking at the US State Department's news briefing, Nuland said Secretary of State Hillary Clinton spoke to Algerian Prime Minister Abdelmalek Sellal to "get his perspective about exactly what's happening on the ground, how the operation is unfolding".
Clinton later told a press conference that the hostage situation was "extremely difficult and dangerous".
"The US extends our condolences to all the families who have lost loved ones in this brutal assault and we remain deeply concerned about those who remain in danger," she said.