WASHINGTON - The United States on Wednesday condemned the attack on British Petroleum (BP) personnel and facilities in Algeria, saying American citizens are among the hostages.

"The best information that we have at this time is that U.S. citizens are among the hostages," State Department spokeswoman Victoria Nuland said at a regular news briefing, refusing to give more details.

She also said she did not have any information on fatalities "at all", as reports said one British and one Norwegian were killed in the attack on a BP oil facility near In Amenas, Algeria, in which 41 foreign workers were taken hostage, including French, British and Japanese nationals.

An armed group related to al-Qaida has claimed responsibility for the attack in a statement released to the Mauritanian news agency. The agency said the move came in response to Algeria's decision to open its airspace to French warplanes to fight the extremist groups in northern Mali.

Nuland said Washington condemned in strongest terms the "terrorist" attack, but did not know the motivation behind it.

She said the U.S. was monitoring the situation closely, and Secretary of State Hillary Clinton had spoken to Algerian Prime Minister Abdelmalek Sellal over the phone.