Four British nationals held as terror suspects in Guantanamo Bay have arrived here after three years of detention in US custody.

The four are Moazzam Begg, Feroz Abbasi, Martin Mubanga and Richard Belmar. They were accused of having links with Al Qaeda.

On their arrival, they were arrested and taken to Paddington Green police station. Groups of protesters chanting and waving placards were outside the station when the men arrived.

Muslim protesters laid a wreath at Paddington Green to remember those still being held in Guantanamo Bay.

A Scotland Yard spokesman said the four had been arrested under Section 41 of the Terrorism Act 2000, covering alleged involvement in the commission, preparation or instigation of acts of terrorism.

The spokesman said they will be allowed a phone call, access to a lawyer and, "due to the unique circumstances", they will be allowed to see a relative.

Deputy Assistant Commissioner Peter Clarke said officers had talked to Muslim representatives and knew there were strong feelings about the case.

But he said: "The fact is that we have an absolute duty on behalf of all communities to investigate the circumstances leading to the men's detention."

He added: "We are totally committed to ensuring that the men are treated properly and fairly."

Begg's father Azmat, who at one stage thought his son would face the death penalty when he was selected for a military tribunal hearing, watched television pictures of the detainees from Birmingham.

"It is a great relief for me," he said. "I am a little bit nervous and emotional."

The Pentagon said the men had been released following a request from the British government.

Britain has assured the US, according to a statement, that "the detainees will not pose a continuing security threat to the US or its allies".

Five other British detainees were freed from Guantanamo last year and were released without charge after questioning by the police in Britain.