A US grand jury has indicted four Orthodox Jewish rabbis and one of their sons for allegedly plotting to kidnap men to force them to divorce their wives.

The indictment follows an undercover FBI investigation into the kidnapping and assaulting of Orthodox Jewish men to extract religious divorces in operations that cost approximately $70,000.

All five have been charged with conspiracy, as well as specific kidnapping and attempted kidnapping charges, US attorney Paul Fishman announced in New Jersey on Thursday.

The conspiracy charge carries a maximum sentence of life in prison and each count is also punishable by a $250,000 fine.

Rabbis Mendel Epstein, 68, Martin Wolmark, 56, Jay Goldstein, 60, and Binyamin Stimler, 38, have been charged with conspiracy to commit kidnapping in October 2013.

In a meeting with undercover agents at his New Jersey home in 2013, Epstein allegedly laid out plans to bundle a particular target into a van and assault him with an electric cattle prod.

Epstein priced the kidnapping at $60,000-70,000 — $10,000 for a rabbinical court to approve the operation — and the rest for “tough guys” to beat up the husband, court documents said.

Two months later in October, Goldstein and Stimler allegedly traveled with others from New York to a warehouse in New Jersey to carry out the kidnapping.

They arrived in two minivans shortly after 8:00 pm, wearing ski masks, Halloween masks and bandanas, and carrying rope, surgical blades, a screwdriver and plastic bags.

Members of the kidnapping ring were then arrested.

Four other people, including two sons of Goldstein, have pled guilty to extortion charges.