LONDON - Six men plotted to kill London subway and bus passengers with bombs made from hydrogen peroxide and flour, two weeks after suicide bombers had slain 52 commuters in the city in 2005, a prosecutor told a jury yesterday.

No one was killed in the attempted bombings of three subway trains and a bus July 21, 2005, because the devices failed to explode.

"We say that the failure of these bombs to explode owed nothing to the intentions of the defendants," prosecutor Nigel Sweeney said in outlining the government's case. "It was simply the good fortune of the traveling public that this day they were spared."

He told jurors: "This case is concerned with an extremist Muslim plot, the ultimate objective of which was to carry out a number of murderous suicide bombings."

The men, who are largely of East African descent, have pleaded not guilty to charges of plotting to bomb London's transport network two weeks after suicide attackers killed 52 commuters in the city.

Muktar Said Ibrahim, 28; Ramzi Mohamed, 25; Yassin Omar, 26; Manfu Asiedu, 33; Adel Yahya, 24; and Hussain Osman, 28 - all from London - deny charges of conspiracy to murder and conspiracy to cause explosions.

Sweeney said Osman had told police the bombs were "a deliberate hoax in order to make a political point" and were not intended to kill. But the prosecutor said forensic scientists had tested the mixture, and "in every experiment this mixture has exploded."

The main explosive charge was 70 percent liquid hydrogen peroxide and 30 percent flour of the type used for chapatis, a type of Indian flat bread, Sweeney said. The detonators contained triacetone triperoxide, an explosive used by Palestinian suicide bombers and by Richard Reid, who tried to detonate a shoe bomb on a U.S.-bound aircraft in late 2001.

Sweeney said the components for the bombs were bought beginning in April 2005, proving the attacks were "not some hastily arranged copycat" of the July 7 attacks.

"It follows from what I have been saying that the evidence in this case shows that the conspiracy had been in existence long before the events of July 7," Sweeney said.

Most of the suspects were arrested in Britain a few days after the failed bombings. Osman fled to Italy and was detained in Rome a week after the attacks.

Eleven other people - including Osman's wife and sister-in-law - have been charged with assisting the accused or failing to disclose information. Their trials are scheduled to take place later this year.

The case is being heard at a heavily fortified courthouse next to London's high-security Belmarsh Prison. The trial is expected to last three to four months.