Having returned home on being granted clemency in August, they told a British newspaper on Saturday that they were beaten, tortured and deprived of sleep in order to extract confessions.
One of them said he had only confessed to the bombings after his jailers threatened to arrest his wife and rape her.
"I truly thought I was going to die. I couldn’t believe that they would treat another human being like that. It was barbaric," Peter Brandon told the Daily Mail.
The five had been accused of carrying out bombings in the kingdom.
Two of the five had been sentenced to death and, if the sentences had been ratified by King Fahd, faced public beheading. The others had been given lengthy prison sentences.
The Saudi embassy in London however has rejected allegations that the Britons were tortured. Instead, embassy officials said they stayed in air conditioned rooms with regular access to visitors, lawyers and whatever food they asked for.
The freed Britons also criticised the UK government's handling of the affair, describing its behind-the-scenes diplomacy as "hushed to the point of silence".