The army says working practices have been altered

Ahmed Mehalba, is the third person to be arrested in connection with suspected security breaches at the detention centre in Cuba, where hundreds of al-Qaeda and Taleban suspects are held.

Mr Mehalba, a US citizen of Egyptian origin, was detained on Tuesday at Boston's Logan airport after arriving on a flight from Cairo.

His court-appointed lawyer said Mr Mehalba would "vigorously defend himself against these charges".

He is scheduled to appear in court again on 8 October.

Border and customs authorities reportedly conducted a random search on Mr Mehalba, uncovering CD-Roms and documents which they suspected of containing classified information about the camp.

Documents related to the arrest were sealed by US magistrate Judge Charles B Swartwood, the Associated Press reported.

Mr Mehalba, 31, is reported to have formerly served in the Army.

AP said he had twice begun - but never finished - a course to become a military intelligence interrogator.

He was medically discharged from the US Army in May 2001 and later joined a private defence contractor, AP reported.

There has been no explanation of his discharge or failure to complete the interrogation course.

Spying allegations

The arrest follows the detention of two US servicemen working at the camp - Senior Airman Ahmad al-Halabi, a translator of Syrian origin, and Captain Youssef Yee, a Muslim chaplain - on allegations of spying.

They have got the right to ask Mr Bush to release the prisoners because we co-operated a lot with them Azmat Begg, father of detainee

Mr Halabi faces 32 charges, including helping the enemy, and is accused of contacting Syrian diplomats - a charge Syria has angrily denied.

Mr Yee is so far being held without charge.

Security was tightened at the camp last week as the US military stepped up its investigation into the alleged espionage.

Meanwhile, families of detainees at the camp urged European parliamentarians to put pressure on the US to resolve their cases.

The father of Moazzam Begg, a Briton, said the UK should use its leverage with Washington to get inmates released.