By AOMAR OUALI and PAUL SCHEMM

Associated Press

ALGIERS, Algeria

--In what could be the first spillover from France's intervention in Mali, Islamist militants attacked and occupied a natural gas complex in southern Algeria on Wednesday. Two people were killed and dozens of others, including several Americans, were reportedly taken hostage.

A militant group claimed responsibility for the rare attack on one of oil-rich Algeria's energy facilities, saying it came in revenge for the North African nation's support for France's military operation against al-Qaida-linked rebels in neighboring Mali. The militants said they were holding 41 foreigners from the energy complex, including seven Americans.

The group--called Katibat Moulathamine or the Masked Brigade--phoned a Mauritanian news outlet to say one of its affiliates had carried out the operation at the Ain Amenas gas field, 800 miles south of Algiers, the Algerian capital.

BP, together with the Norwegian company Statoil and the Algerian state oil company Sonatrach, operates the gas field. A Japanese company, JGC Corp, provides services for the facility as well.

In Rome, U.S. Defense Secretary Leon Panetta declared that the United States "will take all necessary and proper steps" to deal with the attack in Algeria. He would not detail what such steps might be but condemned the action as "terrorist attack" and likened it to al-Qaida activities in Pakistan, Afghanistan and in the United States on Sept. 11, 2001.

Algeria's top security official, Interior Minister Daho Ould Kabila, said that "security forces have surrounded the area and cornered the terrorists, who are in one wing of the complex's living quarters."

He said one Briton and one Algerian were killed in the attack, while a Norwegian and two other Britons were among the six wounded.

"We reject all negotiations with the group, which is holding some 20 hostages from several nationalities," Kabila said on national television, raising the specter of a possible armed assault to try to free the hostages.

It was not immediately possible to rectify the discrepancies in the number of reported hostages. Their identities were also unclear, but Ireland announced that they included a 36-year-old married Irish man. Japan, Britain and the U.S. said their citizens were involved as well. A Norwegian woman said her husband called her saying that he had been taken hostage.

Hundreds of Algerians work at the plant and were also taken hostage in the Islamist attack, but the Algerian state news agency reported they were gradually released unharmed Wednesday in small groups.

The Algerian minister said the militants appeared to be hoping to negotiate their departure from the area, something he rejected. He also dismissed theories that the militants came from across the border in Libya, which is just 60 miles away, or from Mali, more than 600 miles away.

Kabila said the roughly 20 well armed gunmen were from Algeria itself, operating under orders from Moktar Belmoktar, al-Qaida's strongman in the Sahara.