PARIS (Reuters) - Two Frenchmen described as hell Friday their more than two years of detention in the U.S. military prison at Guantanamo Bay, their lawyer said after meeting them for the first time.

Mourad Benchellali and Nizar Sassi had concerns "about the interrogation techniques and medical experiments" at Guantanamo, Jacques Debray said outside the headquarters of the DST domestic intelligence service where the two men were being questioned.

A letter from Sassi said "bizarre" medicines had been given to inmates at night and that one caused some prisoners to break out in spots, Debray told reporters. He gave no other details.

"Each of (the two men) used the same expression, 'We have emerged from hell'," Debray said.

"This is huge for them because it's the first time in two-and-a-half years that they have been able to talk to someone other than a soldier or a police officer, apart from their fellow detainees."

Debray said he would request a full medical examination for his clients when they were brought before anti-terrorism judges Saturday.

Under French law, defense attorneys have access to clients only after 72 hours of detention. Lawyers can see case notes once suspects are brought before an examining magistrate.

Two other former Guantanamo detainees, Imad Kanouni and Brahim Yadel, are being questioned alongside Benchellali and Sassi at DST headquarters.

All four were detained by French authorities on their return to France from the U.S. base in Cuba Tuesday aboard a military plane.

The four were captured during the U.S.-led war in Afghanistan and held by American forces on suspicion of having fought for the ousted Taliban government.

President Jacques Chirac said this week the four had been returned to France after lengthy talks with U.S. authorities and pledged they would face French justice.