NBA referee Tim Donaghy is expected to turn over the names of former colleagues who bet at golf courses, racetracks and casinos during the season, and are involved in football pools, sources told the Daily News.

While the activities are not illegal, they would violate the referees' contracts that prohibit all gambling except at horse tracks in the offseason.

Donaghy, 40, pleaded guilty last Wednesday in federal court in Brooklyn, N.Y., to conspiring to commit wire fraud and conspiring to transmit wagering information across state lines. He reportedly gave federal prosecutors information that will implicate about 20 other referees - about a third of the officiating staff - as part of his cooperation with government officials.

"I don't know if there are 20 NBA refs even that close to Tim Donaghy," a source close to one referee said. "Donaghy was pretty much an outcast by a number of referees, especially the local guys. They threw their arms up a while ago with him. They didn't want anything to do with him, so I don't where this comes from."

The referees are under a league-imposed gag order.