British Foreign Secretary William Hague said on Sunday that a British construction worker held hostage in Nigeria was "likely to have been killed at the hands of his captors" along with six other foreigners. Hague condemned the deaths, first claimed by a Nigerian Islamist group on Saturday, as "an act of cold-blooded murder" and said Britain would work with the Nigerian government to hold those responsible to account. The hostages - from Italy, Britain, Greece and Lebanon - were captured in a raid on a construction site in the northern state of Bauchi. The Italian government has meanwhile ruled out the possibility of a military response to the killings. Militant group Ansaru claimed it had killed the prisoners in an online statement on Saturday. Ansaur is believed to be an offshoot of the infamous Boko Haram network.