Death-row inmates in the nation's prison system are confined to tiny cells with little access to sunlight or exercise, a gross violation of basic human rights, according to a lawyer group citing a recent study carried out with cooperation from prison authorities.

The survey, the first to study the treatment of death-row inmates through a questionnaire, was carried out by the Japan Federation of Bar Associations and polled 79 inmates on death row as of Jan. 11, the association said.

The 58 inmates who responded -- 54 men, three women and one who remained anonymous -- were all held in solitary confinement, many of them in an 8-sq.-meter cell with no view of the outside world, according to the study.