ROME/ATHENS — Seven foreign hostages kidnapped last month by a Nigerian Islamist group from a construction firm compound have been killed, the Italian and Greek Foreign Ministries said on Sunday.

Al-Qaida-affiliated group Ansaru said on Saturday it had killed the hostages seized on Feb. 7 in the northern sate of Bauchi because of attempts by Nigerian and British forces to free them.

It published grainy photos alongside the statement, purporting to show the bodies of a Briton, an Italian, a Greek and four Lebanese workers snatched from the Lebanese firm Setraco. An armed militant stood in front of them.

Nigerian authorities said on Sunday they still had no information on any such killing, and on Saturday they doubted the veracity of the group's statement.

However, an Italian Foreign Ministry statement said: "Our checks conducted in co-ordination with the other countries concerned lead us to believe that the news of the killing of the hostages seized last month is true."

The Greek Foreign Ministry said: "The information we have shows that the Greek citizen is dead," adding, the ministry had informed his family.

Britain and Lebanon declined to comment.

The Greeks and Italians both said there had been no attempt by any government forces to free them.

"We have launched a full investigation to find out what has really happened, but for now we really cannot way whether this report is true or not," police spokesman for Bauchi state Hassan Mohammed Auyo said by telephone.

SECURITY THREAT

Islamist groups operate throughout the north of Africa's top oil producer, where they have become the main security threat after an amnesty ended an uprising by armed groups in the oil-producing southeastern Niger Delta region.

Kidnappings — including some targeting foreigners — have been rife in the southeast for many years, but the gangs there usually seek a payout and hostages tend to be released quickly, while Islamist kidnappings in the north are often fatal.

The hostage taking in the remote town of Jama'are was the largest number of foreigners seized in the mostly Muslim north since an Islamist insurgency intensified two years ago.

Western security officials say growing links between Nigerian Islamists and Saharan groups such as al-Qaida in the Islamic Maghreb has led them to increasingly seek Western targets, rather than local security forces or civilians.

Ansaru declared itself a separate group from the main Islamist insurgent group Boko Haram in January, although security officials believe them to be closely linked.

Its full name is Jama'atu Ansarul Musilimina Fi Biladis Sudan or "vanguards for the protection of Muslims in Black Africa."

Ansaru was suspected of being behind the killing of a British and Italian hostage a year ago in northwest Nigeria, and Britain's parliament has labeled it a terrorist organisation.

It also claimed responsibility for the kidnapping in December of a French national, still missing.

Nigerian authorities are still looking for a French family of seven kidnapped in northern Cameroon and moved over the border by militants who said they were from Boko Haram.

French intervention in Mali has heightened the risk to Western interests in Nigeria, analysts say, and French oil major Total moved its staff from the Nigerian capital Abuja, where Boko Haram also operate, in January.