A British judge sentenced four Al-Qaida-inspired bomb plotters to life in prison Wednesday for their "very nearly successful attempt at mass murder" on London's transit system in 2005, two weeks after suicide bombers killed 52 commuters in the city.

Muktar Said Ibrahim, 29; Yassin Omar, 26; Ramzi Mohammed, 25; and Hussain Osman, 28, must spend at least 40 years in jail before becoming eligible for parole, Judge Adrian Fulford said. A jury convicted the men on Monday of conspiracy to murder for trying to detonate explosives-filled knapsacks on three subway trains and a bus.

Two other suspects, Manfo Kwaku Asiedu, 34, and Adel Yahya, 24, will be retried after the jury failed to reach a verdict.

Prime Minister Gordon Brown said he was investigating why Ibrahim, the group's ringleader, had been allowed to travel to Pakistan - where prosecutors believe he had terrorist training - months before the attacks.

No one was injured in the failed bombings on July 21, 2005. But the judge said that if the bombs had gone off, "at least 50 people would have died, hundreds of people would have been wounded, thousands would have had their lives permanently damaged, disfigured or otherwise, whether they were Christian, Muslim, Jewish, Hindu, Sikh, Buddhist, agnostic or atheist."

"This was a viable, indeed a very nearly successful, attempt at mass murder," the judge said. It was foiled only because, for unknown reasons, the bombs failed to explode.

Prosecutors said that though the planning started long before, the July 21 attacks were a deliberate echo of the July 7 suicide bombings that killed 52 commuters in London. Police suspect, but could not prove, that there were links between the two groups of bombers.

Fulford said the events of July 7 meant the July 21 plotters knew how deadly their bombs were likely to be.

"The family and friends of the dead and the injured, the hundreds, indeed thousands, captured underground in terrifying circumstances, the smoke, the screams of the wounded and the dying - this each defendant knew," the judge said. "They planned this, they prepared for it."

All six defendants denied the charges, saying the devices were duds and their actions a protest against the Iraq War. But police and prosecutors said scientific tests proved the bombs were all viable. They do not know why they did not work.

Sue Hemming, chief anti-terrorism prosecutor, said the men "tried to cause the same level of death and destruction" as the July 7 bombers.

Unlike three of the four July 7 bombers, who were British-born, the July 21 plotters had come to Britain as youths from countries in the Horn of Africa. Some had become British citizens, while others had refugee status.

(China Daily via agencies July 12, 2007)