THE world reacted with revulsion last night to the confirmation that British hostage Ken Bigley had been executed in Iraq.

Mr Bigley's younger brother, Philip, said there was "absolute proof" that the 62-year-old engineer had been murdered after a barbaric three-week ordeal.

Ken Bigley's older brother Stan, 65, choked back tears as he said they hoped "solutions can be found to stop future bloodshed and the loss of innocent lives".

The Bigley family's worst nightmare was realised when militants released a video showing their hostage being beheaded. Reports of Mr Bigley's execution first surfaced on Abu Dhabi TV at lunchtime yesterday.

Footage of the execution surfaced in Baghdad at about 3pm, but it was not screened on TV.

The video showed six hooded and armed men standing behind the kneeling hostage, who witnesses recognised as Mr Bigley from two previous tapes released by the kidnappers.

One of the six then spoke in Arabic for about a minute.

Before committing the murder, the killer said they planned to carry out "the sentence of execution against this hostage" because the British Government "did not meet our demand" to release Iraqi women detained by US-led forces in Iraq.

Then the speaker took a knife from his belt and severed Mr Bigley's head as three others held him down.

Mr Bigley appeared to plead for his life as he was being killed. The recording ended with the killer holding up a severed head.

The news provoked despair and anger from Mr Bigley's Netherlands-based brother, Paul, 54.

He accused Prime Minister Tony Blair of having "blood on his hands".

But last night, it was revealed that Mr Blair had sent secret messages to Ken Bigley's captors in a bid to save him. He made contact through an intermediary who approached the British Embassy in Baghdad only four days ago.

It is thought to be the first time contact has been made with the Islamic fanatics led by Abu Musab al-Zarqawi, and came after Mr Blair said he would listen if they got in touch.

Mr Bigley's wife, Sombat, also known as Lek, and his family were kept informed of the covert communications.

However, al-Zarqawi's ultra hardline group refused to drop its demand for the release of women prisoners in Iraq.

Mr Blair and colleagues have insisted throughout that no women are in British custody in the country.

Last night, Mr Blair said: "I feel desperately sorry for Kenneth Bigley and his family, who have behaved with extraordinary dignity and courage.

"I feel utter revulsion at the people who did this, not just at the barbaric nature of the killing but the way, frankly, they have played with the situation.

"I feel a strong sense, as I hope others do, that the actions of these people, whether in Iraq or elsewhere, should not prevail over people like Kenneth Bigley, who after all, only wanted to make Iraq and the world a better place."

Last night, as the Queen sent a personal message of condolence, Foreign Secretary Jack Straw visited Mr Bigley's family in his home city of Liverpool, on behalf of the Government.

The family appeared to back the Government's efforts in what they called an "impossible situation".

Mr Bigley lost a son in a road accident and his family said: "At least he will now be in the caring hands of his son Paul, who he loved dearly."

As the news emerged from the Middle East, family members gathered at the home of his mother, Lil, 86. Mrs Bigley has endured a three-week nightmare as her son was used as a political pawn by al Qaida-ally Abu Musab al-Zarqawi. She has needed hospital treatment several times.

The wait has also been agony for Mr Bigley's Thai-born wife, who made emotional appeals for mercy