SYRACUSE, N.Y. — Civil rights advocates are asking a federal court to stop a jail in central New York from placing juveniles in solitary confinement.

The New York Civil Liberties Union and Legal Services of Central New York says in a lawsuit Tuesday that the Onondaga County jail has put at least 86 of the 16- and 17-year-olds in small isolation cells more than 250 times since October.

The lawsuit says that violates constitutional rights against cruel and unusual punishment. Many of the juveniles are mentally ill, jailed only because they can’t make bail and are particularly hurt by such isolation.

They spend 23 hours a day in cells, some for minor rule infractions.

The sheriff’s office didn’t immediately reply to requests for comment.

The state agreed recently to limit prison solitary confinement.