The five Greeks are all leading members of Omonia, a movement that Albania suspects of plotting to annex a Greek-inhabited region of southern Albania to Greece. The trial opened last Monday and quickly ran into trouble.
Four of the five accused retracted the confessions they had made after being arrested last April. Panajot Marto, Vangjel Papakristo, Kosta Qirjako and Irakli Sirma told the court that their confessions had been extracted by beatings and by intimidation.
'I had no rest for 72 hours,' Mr Sirma said on Thursday. 'I was questioned without a break and I was also hit twice with a rubber truncheon, once on the head and once on the arm.' Only Theodhori Bezhani stood by his original statement. However, he denied the charges of espionage and illegal possession of weapons.
The state prosecutor said that a delegation from the human rights committee of the Conference on Security and Co-operation in Europe (CSCE) had visited the accused in June and had heard no complaints of mistreatment.
On Monday the prosecutor dropped charges of treason against the five, saying they were based on a Communist-era penal code. The five were arrested after unidentified armed men killed two Albanian soldiers at a military centre near the Greek-Albanian border.
The trial has injected tensions into Greek-Albanian relations. Greece has held up pounds 18m in European Union aid to Albania and Greek police began this week to deport thousands of Albanians working illegally in Greece. Since the fall of Communism hundreds of thousands of Albanians have entered Greece in search of work.
Albania is sensitive about its ethnic Greeks because many Greeks view a region they call northern Epirus as Greek territory. A state of war between Albania and Greece was not formally ended until 1987. Albania puts its Greek minority at 60,000, against Greek estimates of 300,000. Western experts say it probably numbers more than 200,000.