Kidnappers beheaded British hostage Kenneth Bigley after twice releasing videos in which he wept and pleaded with Prime Minister Tony Blair for his life. Bigley's brother Paul blamed Blair, saying yesterday that the prime minister has "blood on his hands." Phil, another brother of Bigley, said that the family had received "absolute proof" of his death. In a statement read on British television, Phil Bigley said the family believed the government had done all it could "to secure the release of Ken." "The horror of these final days will haunt us forever," he said. "Our only consolation is that Ken is now at peace, away from those who are capable of such atrocities." But Paul Bigley turned his anger on Blair. "Mr Blair has blood on his hands," he said in a statement yesterday to an anti-war group in Britain. Blair condemned Bigley's killers and said they must not be allowed to prevail over people trying to rebuild Iraq. "I feel desperately sorry for Kenneth Bigley and his family who have behaved with extraordinary dignity and courage," Blair said in a brief statement he read on national television. Earlier a videotape sent to Abu Dhabi TV showed Bigley kneeling in front of six masked gunmen, according to someone who viewed the footage. One of the militants spoke in Arabic, declaring that the 62-year-old Briton would be slain because his government refused demands to release women prisoners detained in Iraq. The speaker then pulled a knife from his belt and severed Bigley's head as three others pinned him down, said the witness, who asked not to be identified. The tape ended with the killer holding up the severed head. Bigley was seized at his Baghdad home by Iraq's most feared terrorist group, Tawhid Wal Jihad, on September 16 along with two Americans - Eugene Armstrong, 52, and Jack Hensley, 48. The two Americans were beheaded days later. British Foreign Secretary Jack Straw said yesterday that messages were exchanged with Bigley's kidnappers through an intermediary in Iraq. But he said the militants refused to drop their demands, "even though they were fully aware there are no women prisoners in our custody in Iraq." **PHOTO CAPTION*** Members of the public stand for two minutes of silence in memory of slain British hostage Kenneth Bigley in Clayton Square, Liverpool, England, Saturday Oct. 9 2004. (AP)