One of a group of conspirators who tried to detonate homicide bombs on the London transport system in 2005 was sentenced to 33 years in prison Tuesday.

Manfo Kwaku Asiedu, 34, pleaded guilty on Friday to conspiring to cause explosions. Prosecutors said Asiedu lost his nerve and dumped a backpack containing his device in a London park. It was shown to the jury as evidence.

A jury convicted four men of conspiring to murder in July but was unable to agree on verdicts for two other defendants, Asiedu and Adel Yahya, 24.

The charges stemmed from failed attempts to detonate explosives on London subway trains and a bus on July 21, 2005 -- two weeks after homicide bombers killed themselves and 52 commuters in the city.

At the earlier trial, Muktar Said Ibrahim, Yassin Omar, Ramzi Mohammed and Hussain Osman were sentenced to minimum terms of 40 years in prison after being convicted of conspiring to murder.

All six defendants had denied the charges, saying the devices were duds and calling their actions a protest against the Iraq war. But police and prosecutors said scientific tests proved the bombs, made from a volatile mix of hydrogen peroxide and four, all were viable. They do not know why they failed to explode.

Ibrahim, Omar, Mohammed and Osman attempted to set off their bombs on three subway trains and a bus in an echo of the July 7 attacks, but the main charges did not detonate and no one was hurt.

During the trial, Asiedu turned on the others and claimed Ibrahim, the gang's self-proclaimed leader, had wanted the attacks "to be bigger and better" than the July 7 bombs.

Yahya, who had left Britain for Ethiopia several weeks before the attacks, was sentenced Monday to six years and nine months in prison after admitting collecting information likely to be useful to terrorists.

Asiedu was sentenced in London's Kingston Crown Court.