Algerian troops on Thursday (January 17th) launched strikes on a gas complex where Islamists are holding dozens of foreigners, AFP reported.

At least 35 hostages held at the Algerian oil field, along with 15 of their captors, were killed during an air raid, ANI reported.

In a phone call to the Mauritanian website, a member of al-Qaeda's "Battalion of the Masked" claimed that the attack occurred as the captors were moving hostages in trucks to a more secure location.

Seven Western hostages are reportedly still alive at the gas plant.

Former al-Qaeda in the Islamic Maghreb (AQIM) emir Mokhtar Belmokhtar led the Wednesday attack on the Sonatrach-BP-Statoil facility at In Amenas in Tiguentourine. At least two people were killed and six injured in the initial assault, with dozens of workers taken hostage.

The militants said they seized the hostages, who are known to include Algerian, US, British, Irish, Norwegian and Japanese citizens, in retaliation for the French military intervention in northern Mali. Belmokhtar (aka "Laaouar") quit AQIM last month to assemble his own band of suicide bombers in Mali.

Fifteen foreign and 30 Algerian hostages managed to escape earlier on Thursday, Ennahar TV reported. Station owner Anis Rahmani told AFP that the information came from an "official source".

APS also reported that 30 Algerian workers escaped the In Amenas gas field.

The terrorist attack at In Amenas came despite stepped-up Algerian security along the Mali border.

Algerian troops on Monday killed three terrorists in Meskeline, near the borders between Algeria, Niger and Libya. Five gunmen in an SUV were trying to cross Algeria's south-eastern border, the defence ministry said.

The operation was the first carried out by the Algerian army since the start of the military operation in Mali.

Algerian authorities have beefed up security along the 1,400-kilometre border with Mali, and announced the permanent closure of the border as a preventive security measure.

The defence ministry also raised the alert level along the entire border.

"The announcement of the alert that was sent to all units by the Ministry of Defence came after the French military intervention in Mali," Ennahar quoted security officials as saying.

Border guards and the gendarmes will remain in a state of readiness to repel any attack or attempt to penetrate Algerian territory, the paper added.

ANP outposts on the border with Mali were strengthened with additional units.

Furthermore, decisions were made to intensify aerial surveillance along the border and to tighten control over known corridors for arms traffickers.

Algeria will also conduct aerial surveillance of these areas to prevent any infiltration of armed groups trying to exploit the Mali situation.

Meanwhile, with the continuing military operations targeting Islamist strongholds in Mali, Algerian borders saw the arrival of the first convoy of people displaced by the war.

Some 7,000 refugees have already arrived in Tamanrasset. Algerian authorities are continuing to monitor the humanitarian situation.