Shackled and caged Iraq hostage Ken Bigley wept as he called the Prime Minister a liar in a new video issued by his kidnappers last night.

The 62-year old's family expressed their relief at seeing Mr Bigley alive but renewed their pleas for his captors to show mercy.

Mr Bigley, from Liverpool, was dressed in an orange jumpsuit, similar to those worn by the detainees at Guantanamo Bay, in the video screened on Arab TV station al-Jazeera.

He was kneeling behind bars in the small cage and bound by chains as he spoke.

Mr Bigley referred to Mr Blair in the footage and said: "He doesn't care about me. I'm just one, just one person.

"Please, please, help me. I'm begging you, I'm begging you to speak, to push."

He then broke down.

The banner of the Tawhid wal Jihad militant terror group, which has claimed responsibility for the kidnapping, was seen hanging on the wall behind Mr Bigley.

The TV announcer quoted Mr Bigley as also saying: "They don't want to kill me. They could have killed me a week ago."

His captors are demanding the release of female Iraqi prisoners held by the US.

A statement on behalf of the Bigley family said last night: "We once again ask you, please show mercy to my father and release him.

"Please could you pass on once more our love and thoughts to him."

Ken Bigley's message comes a week after a previous video appeal and raises hopes that he could be released.

His brother, Paul, said last night: "He looks unwell but he's alive and he's not a broken man."

A communique from the Middle East has also offered the family hope.

The message, posted on the website Al Qalah.com, claimed Mr Bigley would be freed imminently but warned that others would be kidnapped and beheaded if they failed to withdraw from Iraq.