Conditions at Guantanamo Bay have been criticised

Interior Minister Prince Nayef said the men were handed to Saudi officials after intense efforts to secure the return of all Saudi detainees at the base.

It is thought more than 120 Saudis were taken to the base after the US-led war in Afghanistan. None has been charged.

Their lawyers and families say most of the Saudi prisoners were young and had gone to Afghanistan to participate in relief work.

Prince Nayef said the five men would be tried in Saudi courts "as part of the country's rejection of all kinds of terrorism".

Saudi Arabia is one of several countries which have said publicly they want their citizens home - others include Russia, Sweden, the UK and Pakistan.

The US has said some prisoners might be released if their countries' authorities could guarantee they would deal with them appropriately.

Earlier this month, US defence officials said they would release around one dozen of the 660 inmates from 42 countries held at Guantanamo. But they gave no further details as to their identities.

Thanks given

The release of the prisoners comes three days after suspected al-Qaeda terrorists launched suicide strikes killing 34 people in foreign residential compounds in the Saudi capital Riyadh.

Prince Nayef thanked the US for responding to Saudi requests to release the detainees and said he hoped more would be freed.

He was quoted on the Saudi SPA news agency website as saying that the authorities would continue to press for the return of their citizens.

"This is because we believe in fulfilling our duty to protect our citizens," he said.

"When someone commits a crime, the [Islamic] Sharia courts guarantee a fair trial for him on the basis of justice and truth."