PARIS: Former French President Nicolas Sarkozy described the prison where he spent 20 days as a noisy, harsh “all-grey” world of “inhuman violence” in a book released Wednesday that also offered political advice about how his conservative party should appeal to far-right voters.

In “Diary of a Prisoner,” the 70-year-old says his own tough-on-crime stance has taken on a new perspective as he recounts the uncommon turn in his life after being found guilty of criminal association in financing his winning 2007 campaign with funds from Libya.

The court sentenced him in September to five years in prison, a ruling he appealed. He was granted release under judicial supervision after 20 days behind bars.

The book provides a rare look inside Paris’ La Santé prison, where Sarkozy was held in solitary confinement and kept strictly away from other inmates for security reasons. His loneliness was broken only by regular visits from his wife, supermodel-turned-singer Carla Bruni-Sarkozy, and his lawyers.

Sarkozy wrote that his cell looked like a “cheap hotel, except for the armored door and the bars,” with a hard mattress, a plastic-like pillow and a shower that produced only a thin stream of water. He described the “deafening noise” of the prison, much of it at night.