(CNN) -- Britain, Italy and Greece on Sunday confirmed that hostages from their countries were among seven construction workers reported killed in Nigeria over the weekend. "This was an act of cold-blooded murder, which I condemn in the strongest terms," British Foreign Secretary William Hague said in a statement announcing that a British construction worker was among the dead. Nigerian militant group Ansar al-Muslimeen claimed responsibility for the February kidnappings of the seven construction workers from an office in northeastern Nigeria. The group, widely known as Ansaru, released images of some of the bodies Saturday. Italy's Foreign Ministry said Sunday that it appeared the report of the deaths "is founded." Greece said one of its citizens was among the dead, and that his captors "at no stage either communicated or expressed demands for the release of the hostages."
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"This was an act of cold-blooded murder," British official says
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The hostages had been seized from a construction company office in February
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Their captors blame a raid; Britain says blame "rests squarely with the terrorists"
"I am grateful to the @placeholder Government for their unstinting help and cooperation," he said.