Almost five minutes of footage featuring the 62-year-old engineer is posted on an Islamic website.

The tape comes after Iraq foreign minister Hoshiyar Zebari said it was "likely" that Mr Bigley had briefly escaped.

He was free for up to 12 hours after being helped by one of his kidnappers, according to Iraqi sources.

However, he was recaptured and killed by the fanatical Tawhid and Jihad group after taking a wrong turn, one rebel said.

Details of Mr Bigley's last moments will cause fresh anguish to his family already struggling to come to terms with the atrocity.

In the video, Mr Bigley made a brief statement, saying: "I am not a difficult person. I am a simple man who wants to live a simple life."

British officials have refused to discuss reports that he had fled only to be recaptured.

Speaking for the Iraqi Government, Mr Zebari said: "It is likely but I honestly don't have any confirmation."