The FBI has revived the hunt for the remains of Jimmy Hoffa, with agents digging around in a suburban Detroit field where a reputed mafia captain says the Teamsters labour union boss's body was buried.

Authorities used excavation equipment on the Oakland Township property, about 25 miles (40km) north of Detroit, on Monday. The FBI halted the search for the day at about 7pm and planned to resume efforts on Tuesday.

Robert Foley, the special agent in charge of the FBI's Detroit division, made a few brief comments during a news conference about the latest search for the union leader who went missing in 1975. He said the warrant to search the property was sealed and that authorities wouldn't be disclosing the details of what they were seeking.

Foley didn't mention the name of Tony Zerilli, the reputed mafia captain who told Detroit TV station WDIV in February that he knew where Hoffa was buried. Zerilli, who was promoting a book, Hoffa Found, said the FBI had enough information for a search warrant to dig at the site and that he had answered every question from agents and prosecutors.

Oakland county Sheriff Mike Bouchard said it was his "fondest hope" to bring closure for Hoffa's family and the community.

Jimmy Hoffa. Photograph: AP

Hoffa, Teamsters president from 1957 to 1971, was an acquaintance of mobsters and an adversary of federal officials. The day in 1975 when he disappeared from a Detroit-area restaurant, he was supposed to be meeting with a New Jersey Teamsters boss and a Detroit mafia captain.

Since then, multiple leads to his remains have not panned out.

In September police took soil from a suburban backyard after a tip Hoffa had been buried there. It was just one of many fruitless searches. Previous tips led police to a horse farm north-west of Detroit in 2006, a Detroit home in 2004 and a backyard pool two hours north of the city in 2003.

Zerilli's lawyer, David Chasnick, said his client was "thrilled" that investigators were acting on the information. "Hoffa's body is somewhere in that field, no doubt about it," Chasnick said. He said his client was not making any public comments.

Chesnick said Zerilli told him there used to be a barn in the field, and that Hoffa's body was buried beneath a concrete slab inside the barn.

Zerilli had been convicted of organised crime and was in prison when Hoffa disappeared. But he told New York TV station WNBC in January that he was informed about Hoffa's whereabouts after his release.

Andrew Arena, who was head of the FBI in Detroit until he retired in 2012, said Zerilli "would have been in a position to have been told" where Hoffa was buried.

"I still don't know if this was a guess on his part. I don't know if he was actually brought here by the Detroit [mob] family," Arena said. "It's his position as the reputed underboss. That's the significance."