WASHINGTON: The United States on Wednesday confirmed that American citizens are among hostages being held in Algeria after an attack by Islamist militants near a southern gas field.

"The best information that we have at this time is that US citizens are among the hostages," State Department spokeswoman Victoria Nuland said, but she added that for the safety of the people concerned she would not give further details on how many were held and who they were.

Armed Islamists claiming to have come from Mali earlier Wednesday killed two foreigners, including a Briton, and kidnapped a group of workers in a raid near the Algerian gas field, officials said.

The attack near the In Amenas gas field in southern Algeria appears to be the first reprisal against Western interests for a French-backed offensive against jihadists in neighboring Mali.

Algeria's APS news agency gave a toll of two people killed, including a Briton, and six injured in the dawn attack by suspected Al-Qaeda loyalists in Tigantourine.

A spokesman for the Islamists said the group was holding 41 foreigners hostage, including seven Americans, after the attack.

"Forty-one Westerners including seven Americans, French, British and Japanese citizens have been taken hostage," the spokesman told the Mauritanian News Agency as well as Sahara Media.

He said five of the hostages were being held at the gas plant, while the others were in a housing complex on the site.

The gas field is jointly operated by British oil giant BP, Norway's Statoil and state-run Algerian energy firm Sonatrach.

Nuland condemned the attack and said US Secretary of State Hillary Clinton on Wednesday was talking to Algerian Prime Minister Abdelmalek Sellal about the situation and had also spoken with the US ambassador to Algiers.

The White House said it was also following the situation. "We are monitoring the situation closely and are in touch with the Algerians and our other partners in the region," National Security Council spokesman Tommy Vietor told AFP.