British police on Thursday arrested a suspect in a failed July 21 bomb attack on the London transit system after he was extradited to Britain from Italy.

Scotland Yard said Hussain Osman was charged with attempted murder, conspiracy to murder and explosives offenses for his alleged role in the unsuccessful bombing, which came after a similar attack on July 7 that killed 56 people, including four presumed bombers, and injured 700 others.

Osman, 27, an Ethiopian-born British citizen, was taken into custody at a British air base after arriving on a charter flight from Rome. He was accused of attempting to blow up a crowded London subway train near the Shepherd's Bush station. He was due to appear in a London courtroom on Friday.

Four other men have been charged with attempted murder in the July 21 attacks, which targeted two other subway trains and a double-decker city bus -- the same pattern as in the July 7 bombings. Police said Osman, Muktar Said Ibrahim, 27, Yasin Hassan Omar, 24, and Ramzi Mohammed, 23 -- all Muslim men living in Britain -- carried bombs that did not detonate. Another man, Manfo Kwaku Asiedu, 32, is charged with carrying a bomb in a backpack that was found abandoned in a London park.

Ten other people have been charged with assisting the alleged bombers or withholding information from police investigating the case.

Osman, who was raised in Italy, was arrested at his brother's apartment in Rome eight days after the July 21 attacks when police traced his cell phone calls from Paris, Milan and Bologna, Italy. The apparent ease with which he was able to board a train and leave England, despite massive police surveillance, has raised questions about how strictly Britain should monitor its borders in an era when boundaries within the European Union are disappearing.

His Italian attorney, Antonietta Sonnessa, had argued against his extradition on the grounds that Osman would not receive a fair trial in Britain, where anger and shock over the July bombings still runs deep. An Italian judge ordered his extradition last week.

Following Osman's arrest in Rome, Italian investigators leaked detailed accounts of their questioning of him. Because British authorities and media outlets can face prosecution for disclosing details of an ongoing criminal investigation, those leaks have been among the most substantial information about the investigations to emerge since the men were arrested.

According to Osman's attorney and Italian authorities quoted in newspapers in Italy, Osman said Ibrahim was the group's ringleader. Osmanreportedly said that he and Ibrahim met at a gym in Notting Hill, where they worked out and practiced martial arts and where Ibrahim showed him videotapes of the war in Iraq. Osman said Ibrahim told him they "had to do something big" in response to the U.S.-led effort in Iraq, in which Britain is the main U.S. partner, Italian media reported.

Osman has repeatedly said the July 21 bombs were not intended to hurt anyone, and Sonnessa quoted him as saying his device was made only of flour -- claims that British authorities dismissed in London news reports.

Osman also reportedly said that global networks of Islamic radicals were not involved in the attacks. A top al Qaeda official, Ayman Zawahiri, this week said the group was responsible for the July 7 attacks, although he praised the bombings in two earlier statements without directly asserting responsibility. Police are were investigating whether radical Islamic groups were involved in the attacks, and whether the July 7 and July 21 incidents were connected.

Osman's role with international radical groups has also been under investigation. A Saudi official said in an interview in August that Osman placed a phone call to Saudi Arabia just before he was arrested. The official also said Ibrahim had visited Saudi Arabia in 2003 and told friends he was going there to receive training.

Hussain Osman arrives at Rome's Ciampino airport in police custody.