American Civil Liberties Union lawyer David McGuire said the inmates are improperly denied access to group religious services, group recreation, use of gym equipment and visits with friends and family.

In his letter to the Department of Correction, McGuire noted that complaints about conditions prompted the inmates to go on a hunger strike last May.

"Officials have both verbally and in writing promised to secure certain privileges for the death row inmates in exchange for the cessation of the most recent hunger strike," McGuire. "A number of these promises have not been fulfilled."

The inmates, who are housed in the same unit at the Northern Correctional Institution, are seeking privileges including the chance to send photographs of themselves to loved ones, and to walk unshackled during certain times, including to and from the shower.

Many of the privileges were taken away after a 1998 suicide attempt by Michael Ross, who was executed in 2004, and the discovery of a letter by inmate Daniel Webb plotting an escape attempt.

Both group recreation and the opportunity to eat in a common room with other death row inmates were revoked in 1998.

Inmates say they had been promised that a pastor would be allowed to visit them once a week, but those visits have not consistently been provided, according to the letter.

"It cannot be asserted that safety concerns justify the denial of access because religious service is provided sporadically, and without relation to inmate behavior," McGuire wrote.