A U.S. District Court judge yesterday dismissed a racketeering lawsuit against a city dockworkers union that federal prosecutors accused of conspiring with two powerful New York mob families.

The ruling, by Judge Leo Glasser of Brooklyn, is the latest action in a decades-long government probe of alleged Mafia influence at ports in New York, New Jersey, and Miami.

Prosecutors said that between 1995 and 2002, the International Longshoremen’s Association colluded with the Genovese and Gambino crime families to rig contract bids and elections, orchestrate investment kickback schemes, and launder money.

Judge Glasser ruled that the government’s complaint failed to “sufficiently specify” its rationale for applying the federal Racketeer Influenced and Corrupt Organizations Act to its mail and wire fraud charges, and that it did not appropriately cite any evidence that would satisfy RICO standards.

The judge further ruled that other motions to dismiss the amended complaint were moot, and that he would allow the government to file a second amended complaint within 60 days.

An attorney for the longshoremen’s union, Howard Goldstein, said he was delighted by the judge’s decision.