(Reuters) – An Oklahoma man was arrested after what he thought was an attempt over the weekend to bomb an Oklahoma City bank building as part of an anti-government plot, U.S. prosecutors said on Monday.

The Federal Bureau of Investigation arrested Jerry Drake Varnell, 23, on Saturday after an undercover agent posed as a co-conspirator and agreed to help him build what he believed was a 1,000-pound (454 kg) explosive.

Varnell had initially planned to bomb the U.S. Federal Reserve in Washington in a manner similar to the 1995 explosion at a federal building in Oklahoma City that killed 168 people, according to a complaint.

FBI agents arrested Varnell after he went as far as making a call early on Saturday morning to a mobile phone he believed would detonate a device in a van parked next to a BancFirst Corp building in downtown Oklahoma City, the complaint said.

“This arrest is the culmination of a long-term domestic terrorism investigation involving an undercover operation, during which Varnell had been monitored closely for months as the alleged bomb plot developed,” federal prosecutors said in a statement. “The device was actually inert, and the public was not in danger.”

Varnell, of Sayre, Oklahoma, was charged with malicious attempted destruction of a building in interstate commerce. He is expected to make his first court appearance in federal court in Oklahoma City on Monday afternoon.

(Reporting by Joseph Ax in New York and Bernie Woodall in Fort Lauderdale, Florida; Editing by Chizu Nomiyama and Lisa Von Ahn)