NBA referee Tim Donaghy, under investigation by the FBI for betting on games he worked, had local law officials at his Florida home Sunday because of threatening phone calls he's received, according to the New York Post.

Three squad cars from the Manatee County Sheriff's Office arrived at Donaghy's home in Bradenton, Fla.

``Our concern is for his safety and his family's safety,'' Sheriff's Lt. Robert McNealy told the newspaper for a story in Monday's editions. ``We are definitely going to share any information we get with the FBI.''

Authorities are examining whether the referee made calls to affect the point spread in games on which he or associates had wagered thousands of dollars over the past two seasons. Authorities say the referee had a gambling problem and was approached by low-level mob associates through an acquaintance.

The Daily News reported Sunday, citing unidentified law enforcement sources, that Donaghy will co-operate with authorities and possibly name other officials and players involved in the betting scandal.

On Monday, the newspaper reported that former neighbours of Donaghy's in Pennsylvania say they were approached more than a year ago by a private investigator they believed was hired by the NBA to check into Donaghy's gambling habits.

Kit Antsey, a real estate agent in West Chester, Pa., who helped Donaghy buy a home, told The Daily News a private investigator contacted him 18 months ago and asked him whether Donaghy bet on sports and at an Atlantic City casino.

However, the New York Times reported Monday, citing two unidentified people briefed on the investigation, that the NBA didn't know about Donaghy's betting or whether he affected the outcome of games until after the season.

The Times and the Daily News also reported NBA commissioner David Stern plans to speak publicly about Donaghy this week, maybe as soon as Monday.