Five British men held in U.S. military detention in Guantanamo Bay (search), Cuba, returned Tuesday to England, where four were immediately arrested on suspicion of involvement in terrorism and one was released.

Jamal al-Harith, 37, was released after he was questioned by immigration authorities.

"He's an innocent man and he wants to know why was he kept in custody for so long," said his lawyer, Robert Lizar said. "He is looking forward to seeing his family again very much. However he wants the U.S. authorities to answer for what he has suffered."

A Metropolitan Police official said the four were arrested on suspicion of involvement in the commission, preparation, or instigation of acts of terrorism. He did not give further details.

The five men were among nine Britons whose captivity at the U.S. military prison had caused friction between the two close allies.

Royal Air Force C17 (search) landed Tuesday night at Northolt Royal Air Force Base (search) west of London. Armored police vans awaited the flight.

The vans were driven aboard the giant cargo carrier, then sped away in a convoy to Paddington Green police station, where terrorist suspects are held.

All the men would undergo medical examinations before any questioning, said Deputy Assistant Commissioner of the Metropolitan Police, Peter Clarke, the national coordinator for anti-terrorism.

"Everything that happens to these men from the moment they arrived on U.K. soil will be entirely in accordance with United Kingdom law and the normal procedures in these cases will be followed to the letter," Clarke said.

Police said the men would be allowed a telephone call and have access to a lawyer of their choosing.

Britain had demanded that its nine nationals, some of whom had been held for more than two years without charge or access to lawyers, either be given fair trials or returned home.

With the release of the five after months of talks between British and U.S. officials, negotiations will continue over the remaining British detainees at Guantanamo.

Foreign Secretary Jack Straw has said prosecutors would decide if the men would be charged.

Some legal experts doubt they can be tried in Britain since information gleaned from interrogation at Guantanamo would be inadmissible in court. It is also unclear whether British courts have jurisdiction over alleged criminal acts in Afghanistan, unless crimes of terrorism or treason could be proven.

"These returnees have been through an appallingly lengthy and unjust ordeal in which they were deliberately held in a legal limbo by the U.S. authorities," Iqbal Sacranie, secretary-general of The Muslim Council of Britain, said Tuesday.

About 640 prisoners are held at Guantanamo on suspicion of links to the fallen Taliban regime of Afghanistan or the Al Qaeda terror network.

The United States says the suspects are "enemy combatants" subject to different legal rules than prisoners of war. The U.S. Supreme Court has agreed to hear arguments whether they should be allowed to challenge their detention in American courts.

The government announced last month that five of the Britons held at Guantanamo would be released.

They had been identified as Rhuhel Ahmed; Jamal al-Harith; Tarek Dergoul; Asif Iqbal; and Shafiq Rasul.

Families and lawyers of the five returned men have insisted they are innocent.

The four who remain at Guantanamo are Moazzam Begg; Feroz Abbasi; Richard Belmar; and Martin Mubanga.

Begg and Abbasi had been listed as some of the first detainees likely to face a military commission, a possibility Britain has criticized.

Blair's official spokesman said Tuesday that the Britons should only be tried in the United States if they had access to legal representation and rights of appeal, which he said was not the case now.