BOSTON — The Satanic Temple has sued Boston after the city council declined to allow Satanists to deliver an invocation at the start of its meetings.

The Salem-based group, which has lodged freedom of religion challenges nationwide, said Tuesday that the council’s policy for its opening prayer is discriminatory and unconstitutional because it does not permit prayer from every religious organization that wishes to deliver one.

Satanists have asked to give the opening invocation on at least three occasions, and each time they were informed the council doesn’t accept requests, the organization said. Council policy allows each council member to invite a speaker of their choice to deliver the opening prayer before each meeting a few times a year, according to the organization.

The Satanic Temple, in its federal lawsuit filed last week, argues that the council policy violates the city’s public accommodations statute, which states that any place serving a public function is entitled to protection from discrimination. It also violates the U.S. Constitution’s Equal Protection Clause, which it argues guarantees all religions an equal opportunity to participate in free-speech forums.

Mayor Marty Walsh’s office declined to comment, citing the pending litigation. An email seeking comment was sent to representatives for the council.