Seven foreign hostages killed, claims Nigerian Islamists

However, there was no immediate confirmation from Nigerian authorities or the countries the hostages were said to be from.

An official from the construction company, Setraco, told AFP he was aware of the report but could not confirm it.

According to SITE, "Al-Qabidun 'Ala al-Jamr (Grippers of Embers) Media Foundation, an affiliate of the Sinam al-Islam Network, issued the communique in Arabic and English on March 9, 2013, and also provided screen captures of a forthcoming video showing the dead hostages."

"In the communique, the group stated that the attempts by the British and Nigerian governments to rescue the hostages, and their alleged arrest and killing of people, forced it to carry out the execution," SITE said.

Police last month said the victims of the February 16 kidnapping in Bauchi state included four Lebanese, one Briton, a Greek citizen and an Italian. A company official later said the Middle Eastern hostages included two Lebanese and two Syrians.

Ansaru, considered a splinter faction of Islamist extremist group Boko Haram, claimed responsibility for the kidnapping two days after the abduction.

In an email statement sent to journalists announcing the claim, Ansaru said it has "the custody of seven persons, which include Lebanese and their European counterparts working with Setraco," the Lebanese-owned company targeted in the attack.

The two-paragraph statement in English cited "the transgressions and atrocities done to the religion of Allah ... by the European countries in many places such as Afghanistan and Mali".

Ansaru has been mentioned in connection with several kidnappings, including the May 2011 abductions of a Briton and an Italian working for a construction firm in Kebbi state, near the border with Niger.

The victims were killed in March 2012 in neighbouring Sokoto state during a botched rescue operation.

It also claimed the December kidnapping of a French engineer in Katsina state, bordering Niger. The victim's whereabouts remain unknown.

Seven members of a French family, including four children, were also abducted last month in Cameroon where authorities said they were then taken over the border into restive northeastern Nigeria. Their whereabouts also remain unknown.

France has blamed that kidnapping on Boko Haram. A video emerged on YouTube on February 25 showing the family and the abductors, who claimed to be from Boko Haram.

The video however was significantly different from previous Boko Haram videos and the group had never before claimed a kidnapping despite carrying out a deadly insurgency in northern and central Nigeria that has killed hundreds.

Ansaru has appeared to focus specifically on kidnapping foreigners, though it has not been known to have claimed the abduction of the French family.

Nigeria is Africa's most populous nation and largest oil producer, roughly divided between a mainly Muslim north and predominately Christian south.

Violence linked to Boko Haram's insurgency has left some 3,000 people dead since 2009, including killings by the security forces.

On Saturday, a military spokesman in the country's northeast claimed 52 Boko Haram members had been killed and 70 arrested over the last 10 days, while two soldiers were left dead.

There was however no independent confirmation and statements from the military, accused of major abuses in the fight against Boko Haram, are often unreliable.