Thirty-four hostages have been killed and 26 freed during an attack by the Algerian military on the site where Islamist gunmen were holding a group hostage, dpa reported according to France Info radio.
France Info radio quoted sources as reporting that 26 hostages were freed, but said the situation was still very unclear.
A France 24 correspondent in Algeria said security sources had denied any airstrike on the site.
The information could not be immediately confirmed.
The spokesman earlier told ANI: "Helicopters from the Algerian army have begun bombing the complex where more than 40 Western hostages are being held, causing injuries among them."
Algerian officials had yet to confirm that the army, which has surrounded the site, had launched a raid to try to free the hostages.
The gunmen said they were holding 41 Western workers; the government estimates the number at half that.
Ennahar television reported that 15 foreigners, including a French couple, had succeeded in escaping the site Thursday, along with about 30 local Algerian staff.
The official APS agency confirmed the escape of the Algerians, but not those of the foreign hostages.
The hostage-takers, who are led by Mokhtar Belmokhtar - a notorious one-eyed Algerian-born terrorist affiliated to the al-Qaeda in Islamic Maghreb (AQIM) group - had threatened to kill the hostages if the army intervened and demanded negotiations.
"We will kill all the hostages if the Algerian army tries to free them by force," a spokesman told ANI.
Two people, one British and one Algerian, were already dead and six people were injured when the militants launched the attack on the workers' compound early Wednesday.
British Foreign Secretary William Hague condemned the Briton's "cold-blooded murder" and said he had sent a rapid deployment team to Algeria to "strengthen our embassy there and help them in their work."
British, Irish and Japanese hostages who spoke to broadcaster Al Jazeera by telephone early Thursday had appealed to the army to hold its fire to allow negotiations to begin.
A 52-year-old French hostage, who spoke to Sud Ouest newspaper by telephone, sent a message of reassurance to his family, saying: "It's ok. We are being treated well."
Confirming the presence of French hostages for the first time Thursday, President Francois Hollande said the situation was evolving "from hour to hour" and that he had "every confidence in Algerian authorities" to resolve it.
US, Norwegian, Romanian and Austrian nationals are also in the group.
The attackers have demanded an end to France's intervention in neighbouring Mali and said they want to also punish Algeria for allowing French warplanes to overfly the country, according to statements reported by ANI.
AQIM is one of three rebels groups being targeted in the French campaign.
Algeria, which has a long history of combating Islamist terrorism, has ruled out negotiating with the group.
Interior Minister Dahou Ould Kablia told local television on Wednesday that the authorities "will not answer the terrorists' demands."
In Amenas gas field, one of Algeria's biggest, is operated by a consortium comprising Britain's BP, Norway's Statoil and Algerian state company Sonatrach.
Statoil said Thursday that production at the facility had been shut down. It said 12 Statoil employees were unaccounted for, including nine Norwegians.
BP, which has "a number" of staff among the hostages, described the situation as "unresolved and fragile."
"BP is in regular contact with the Algerian authorities, with our partners at Statoil and with other companies involved in the situation," it said dpa