NEW ORLEANS (AP) — A Louisiana jail routinely humiliates suicidal prisoners by forcing them to wear skimpy shorts that say ‘‘Hot Stuff’’ on the rear and confines them in tiny ‘‘squirrel cages’’ for weeks at a time, a civil liberties group said Thursday.

In an open letter to St. Tammany Parish officials, the American Civil Liberties Union of Louisiana says it is unconstitutional for the parish jail to confine prisoners in cages that are three feet wide, three feet long and seven feet tall. Guards and prisoners refer to them as squirrel cages, the ACLU says.

‘‘We understand that the cages have been frequently used to hold more than one prisoner at a time, and that staff often ignore prisoners’ requests to use the bathroom, forcing people to urinate in discarded milk cartons,’’ wrote Marjorie Esman, the group’s executive director.

A St. Tammany Parish code requires dogs to be kept in cages that are at least six feet wide and six feet deep, larger than the cages that prisoners are using, Esman wrote.

The ACLU also claims suicidal prisoners are forced to wear bright orange ‘‘short shorts’’ with ‘‘Hot Stuff’’ scrawled in pen on the rear.

‘‘These conditions are clearly unconstitutional,’’ Esman wrote.

The group is calling on Sheriff Jack Strain and Parish President Kevin Davis to stop using the cages and create more humane housing for suicidal prisoners.

A sheriff’s office spokesman didn’t immediately return a call for comment.

In an emailed statement, St. Tammany Parish chief administrative officer William Oiler said the parish had not previously received complaints. ‘‘St. Tammany Parish has no knowledge of, or authority over, the day-to-day operations of the St. Tammany Parish jail,’’ Oiler said. He said parish officials would talk with Strain about the issue.

ACLU attorney Katharine Schwartzmann said the allegations are based on interviews with current and former prisoners as well as testimony from the jail’s medical director, Demaree Inglese.

‘‘This is basically an attempt to avoid litigation,’’ Schwartzmann said. ‘‘We’ve been getting letters from prisoners about this for quite a while.’’

In April, the ACLU filed a federal lawsuit that claims dozens of accused criminals with mental illnesses are languishing in parish jails for months when they should be getting treatment at a state-funded hospital. The suit says the Feliciana Forensic Facility in Jackson, La., hasn’t been adequately funded and doesn’t have room for all the detainees in need of treatment that jails aren’t equipped to provide.