By Emma Jane Kirby BBC correspondent in Geneva

The International Committee of the Red Cross has renewed its appeal to the United States to clarify the status of hundreds of terror suspects it is holding without charge.

The call came on the anniversary of the first Red Cross visit to the US military base at Guantanamo Bay in Cuba, where more than 600 people are imprisoned.

They are designated by the US as illegal combatants.

The Red Cross says they should be classed as prisoners of war and treated as individuals, subject to the protection of the Geneva Conventions.

Many international agencies, including Amnesty International, have called on the US Government to either release the men being held or to charge them with a crime.

The ICRC steers clear of such public criticism but stresses that it is continuing to put pressure on the US authorities to give each prisoner a fair tribunal.

Letters

Over the past 12 months, ICRC teams have spent about 33 weeks in Guantanamo Bay interviewing prisoners and checking basic issues such as food, hygiene facilities and access to exercise and fresh air.

Camp Delta

About 600 alleged al-Qaeda and Taleban fighters being held Inmates from 40 countries Suspects classified as unlawful combatants

Most of those held were detained in Afghanistan.

They are not allowed direct contact with their relatives so, over the past 12 months, Red Cross workers have facilitated the exchange of 3,300 personal messages between the prisoners and their families.

The United States refuses to release the names of any of those held so the censored letters are often the only way families can confirm their relatives are being held at the base.

Procedure

A spokesman for the Red Cross said the organisation had repeatedly told the US Government that each prisoner should be given access to an independent and impartial tribunal to determine his status.

"What is important for us is that we think there should be a procedure put in place which answers that question for each individual internee who is at Guantanamo at the moment," the spokesman said.

"On the basis of this determination of the status, the US can then see how they want to proceed in the case of each individual detainee."

The ICRC, which has just completed its fourth mission to Guantanamo Bay, says it will continue to carry out regular visits to the camp as long as people are imprisoned there.