A Muslim group is suing a South Jersey city for allegedly using land-use regulations to prevent the expansion of a mosque, violating federal law and constitutional protections for religious liberty.

The nonprofit Garden State Islamic Center says the City of Vineland, in Cumberland County, has illegally refused to issue a certificate of occupancy needed to open the recently constructed second floor of its mosque, which has 220 members.

The city has "unreasonably and unilaterally rescinded the pre-construction permits" and "engaged in a pattern and practice of discriminatory conduct, which extends over the course of a decade, aimed at halting the operation" of the center's "house-of-worship and religious education building," says the lawsuit, filed in U.S. District Court in Camden on Tuesday.

The lawsuit, which also names the city's health director, its environmental health specialist, and tax collector, seeks to enjoin the defendants from refusing to issue the necessary permits and  from "interfering with the operation of GSIC's house of worship and religious facility." It also seeks punitive damages and the appointment of a federal monitor to ensure the city's compliance with a court order.

Vineland has threatened to shut down the mosque and issued Garden State Islamic Center a $50,000 property tax bill in 2015, even though the group is a tax-exempt religious organization, the suit alleges.

The city did not respond to a request for comment Wednesday.

Members are still able to worship but "the entire project has been put under a big cloud," Aymen A. Aboushi, the group's attorney, said Wednesday.

In addition to raising constitutional objections, the suit says the city's actions violate the Religious Land Use and Institutionalized Persons Act of 2000. In November, the Justice Department sued Bernards Township, Somerset County, under the same law, alleging the town denied application for a mosque out of prejudice.

The law protects houses of worship from zoning discrimination.

Litigation between Vineland and Garden State Islamic Center dates back to 2009, when the group first sought permits to build the mosque.

After the city planning board rejected its site plan application, the Islamic Center filed a complaint in state court. The parties settled, and in 2011 the planning board approved the group's site plan for a three-level house of worship.

In 2012 the city "inspected and approved" the center's septic system and issued a temporary certificate of occupancy, allowing the center to open a one-level mosque, according to the suit.

At issue now is a debate over sewage flow.

Last year the center applied for permits to build a second floor for such things as lecture rooms, a library, offices, and restrooms.

The suit alleges that the city wrongly determined that the mosque's sewage flow exceeded 2,000 gallons per day, a threshold that requires state approval for new septic and waste management systems.

Garden State Islamic Center says that calculation grossly overestimates how many people visit the building each day. Even if all 220 members visited daily — at most, some 80 worshipers come for two hours on Fridays — the sewage flow would be 660 gallons per day, the lawsuit says.

The group also alleges that a Christian church with a "substantially larger" facility and twice as many members was not subject to the same requirements by the Cumberland County Health Department when the church, in Deerfield Township, gained septic system approval in the last 18 months.

The county Health Department used the same methodology as the Islamic center in calculating water use, the suit says, while Vineland's has "never been imposed upon other religious and secular" institutions.