Suspected terrorists at Guantanamo Bay who are released into the hands of European authorities are not being allowed to escape justice.

Three men held for up to six years for their links to Al Qaeda were handed to British authorities this week and were immediately arrested by British police en route to Britain. On their arrival, they were interrogated on suspicion of preparing, commissioning, or instigating acts of terrorism.

One of them yesterday became the subject of an urgent extradition request from the Spanish government.

The arrest of the three, residents of Britain but not British citizens, all of whom the Pentagon describes as “extremely dangerous,” comes in the same week five Frenchmen released from Guantanamo were found guilty in Paris of terrorist offenses.

All were among those handed to European authorities as part of President Bush’s plan to draw down the number of prisoners at Guantanamo and close it as a detention center. Three hundred remain imprisoned there.

The release of suspects with European citizenship or residency is made on condition that they are kept under surveillance and are not free to commit acts of terror. Two detained by the British on Wednesday, Omar Deghayes, 38, a Libyan, and Abdennour Sameur, 34, an Algerian, were taken to Paddington Green maximum security police station.

Mr. Deghayes is alleged to be a “jihadi veteran” of the Bosnian war and an associate of Salaheddine Benyaich, a leader of the Casablanca suicide bombers who killed 45 in March. His Guantanamo file says “he has direct connections to Al Qaeda operatives in Europe.”

Mr. Sameur, who attended the Finsbury Park mosque in North London, once attended by Richard Reid and Zacarias Moussaoui, stands accused of undergoing terrorist training in Afghanistan. He was detained after fleeing to Tora Bora, the mountain caves that harbored Osama bin Laden after his flight from the American invasion of Afghanistan.

Under interrogation at Guantanamo, Mr. Sameur confessed to prior knowledge of the attacks of September 11, 2001, though he later said he invented the story after being tortured.

The third suspect, Jamil el-Banna, 45, a Palestinian Arab with a Jordanian passport, was held under British border controls. According to Pentagon sources, he is suspected of “a long-term association” with Abu Musab al-Zarqawi, the leader of Al Qaeda in Iraq who beheaded the British engineer Ken Bigley in October 2004. Zarqawi was killed by American forces in June 2006. Although Britain negotiated the suspects’ release from Guantanamo, their return “does not imply a commitment on our part that they can remain permanently in the U.K. and their immigration status will be reviewed,” the Home Office said. Mr. Deghayes and Mr. Sameur were captured in 2001 by American forces in Afghanistan and Pakistan, respectively. Mr. Deghayes is accused of appearing in a propaganda video of Islamist terrorists in Chechnya and consorting with Al Qaeda fighters. His lawyer, Clive Stafford Smith, has said he is a victim of mistaken identity.

Mr. Banna, who is wanted in Spain for allegedly belonging to an Al Qaeda terror cell, the Islamic Alliance, between 1996 and 2001, went before magistrates yesterday and was conditionally freed until the extradition hearing on January 9. He was granted bail of $100,000, which was met in part by the actress Vanessa Redgrave. If he is found guilty in Spain, he faces 15 years in prison.

MI5 failed to recruit Mr. Banna as an informant against Abu Qatada, a London-based Islamist cleric accused of consorting with terrorists who planned the September 11 attacks and who is currently in a British prison awaiting deportation to Jordan.

Mr. Banna was detained by American forces in the Gambia in November 2002 after a tip-off by MI5, which told the CIA that he was a “veteran of the Afghan-Soviet war” who funded Mr. Qatada. Because of his links to Mr. Qatada, a Spanish judge ordered his extradition in 2004.

Ten other Guantanamo detainees released to Britain this year must wear electronic ID tags, observe strict curfews, and have their access to the Internet and cell phones restricted.

On Wednesday, five suspects released from Guantanamo were found guilty of “criminal association in relation to a terrorist enterprise” and given prison sentences of one year and suspended sentences. Because they spent more than a year at Guantanamo, they were set free.