Malian National guards patrol on January 16, 2013 at a military airbase in Bamako as president Dioncounda Traore visit French troops. French troops battled Islamist rebels in Mali today in a war which escalated as Al Qaeda-linked fighters claimed to have taken 41 foreigners hostage in a retaliatory attack in neighboring Algeria. (Photo: ISSOUF SANOGO/AFP/Getty Images)
UPDATE: (ALGIERS, Algeria) - The hostage situation in an Algerian natural gas complex appeared to reach a dangerous crescendo Thursday, with Islamic militants claiming that Algerian helicopter attacks have left 35 hostages and 15 captors dead.
Details were still emerging Thursday morning and there was no official confirmation from U.S. or other governments involved on the reported deaths. The British Foreign office did confirm that they were aware of an "ongoing military operation."
A diplomatic source confirmed to CBS News that the Algerian military had a plan to retake the facility and that there have been casualties among both the terrorists and hostages, including multiple deaths.
A British security source, citing a contact close to the scene, told CBS News "that the Algerians were firing from helicopters at anything that moved," but could not confirm any deaths.
Meanwhile, multiple sources reported the earlier escape of some hostages, but details differed. An employee at the facility, partly operated by BP, told CBS News that 26 Algerians and four foreigners, including one American, had escaped, citing a briefing from BP officials. Two British and one French hostage accounted for the other foreigners.
One Algerian security official told the Associated Press on Thursday that 20 foreigners had managed to escape, including some Americans and Europeans.
Those reports were also unconfirmed by government officials.
Al-Qaeda-linked militants stormed the natural gas complex in the Sahara Desert on Wednesday, seizing up to 41 foreign hostages. Algerian forces have surrounded the militants at the plant since then, and have rejected demands for safe passage.
The group claiming responsibility -- called Katibat Moulathamine or the Masked Brigade -- said the attack was in revenge for Algeria's support of France's military operation against al Qaeda-linked rebels in neighboring Mali. Militants phoned a Mauritanian news outlet to say one of its affiliates had carried out the operation at the Ain Amenas gas field, and that France should end its intervention in Mali to ensure the safety of the hostages.