LAGOS (Reuters) - A Nigerian Islamist group that killed seven foreign hostages it had been holding since February has posted a video of their bodies on the Internet.

Italian and Greek authorities confirmed on Sunday that a British, an Italian, a Greek and four Lebanese construction workers abducted in northern Nigeria's Bauchi state last month had been killed by their captors.

British Foreign Secretary William Hague said it was "very likely" they were dead, calling it "an act of cold blooded murder". Nigerian authorities have thus far not commented.

The national police spokesman and a spokesman for police forces in Bauchi state both said on Monday they could not yet confirm or deny the killings.

The silent video published by the al-Qaeda linked group, Ansaru, and dated March 9 shows a gunman standing next to a pile of bodies, then a series of close-ups of their faces lit up by a torch.

It carries the Arabic title "The killing of the seven Christian hostages in Nigeria" although the religion of the captives was not clear.

A caption underneath says in Arabic and in English: "In the name of Allah Most Beneficent Most Merciful".

The workers were seized from the premises of the Lebanese firm Setraco in the remote town of Jama'are in Bauchi state.

Willy7: Hope this cowards realise that we are in the drones season?Let them keep fetching ant infested firewoods,very soon d ants will start biting.I just wonder what kind of religion supports killing and still talk about merciful.

. . ."In the name of Allah Most Beneficent Most Merciful".