The complaint, filed in U.S. District Court in Newark on behalf of more than 200 Indian construction workers at the temple, alleges "shocking violations of the most basic laws applicable to workers in this country, including laws prohibiting forced labor."

The suit, filed by five of the workers, accuses their employer, Bochasanwasi Shri Akshar Purushottam Swaminarayan Sanstha, or BAPS, and related entities of recruiting them in India, bringing them to the United States and forcing them to work on the temple for more than 87 hours a week for $450 a month, or about $1.20 an hour.

New Jersey's minimum wage is $12 an hour and U.S. law requires the pay rate for most hourly workers rise to time-and-a-half when they work more than 40 hours a week.

The suit says the workers were kept under constant watch and were threatened with pay cuts, arrest and return to India if they spoke to outsiders.

On Tuesday, FBI agents visited the sprawling ornate temple in rural Robbinsville, just east of Trenton.

"We were there on court-authorized law enforcement activity," Doreen Holder, a spokeswoman for the Federal Bureau of Investigation field office in Newark, confirmed by telephone.

Holder declined to say how many agents were on the premises or elaborate on their mission.

A spokesman for BAPS, which describes itself as a socio-spiritual Hindu organization, issued a statement saying, "We were first made aware of the accusations this morning, we are taking them very seriously and are thoroughly reviewing the issues raised."

The suit said the BAPS entities own the land where the temple was built and arranged for its construction. The temple has been open for several years, but work on extending it is ongoing.

The plaintiffs, who claim to have worked on the temple as stone cutters and other construction workers as far back as 2012, said that in India, they belonged to the Scheduled Caste, formerly considered "untouchables" and socially ostracized.

Once on their construction jobs, the complaint said "they were forced to live and work in a fenced, guarded compound which they were not allowed to leave unaccompanied by overseers affiliated with (BAPS)."

The suit, which also claims the workers were falsely classified as religious workers and volunteers when they entered the country, seeks "the full value of their services" as well as unspecified damages and other compensation.