Mobsters exert a strong hold on hundreds of union locals across the country, and the problem is getting worse, the government's top organized crime fighters told Congress yesterday.

Acting Deputy Attorney General Benjamin Civiletti told the Senate governmental affairs permanent investigation subcommittee there is "an awful lot of racketeering" going on, with an estimated 300 union locals "severely influenced by racketeers."

He estimated there are an estimated 75,000 local unions nationwide, and only about one half of 1 percent are under the influence of organized criminals. Most of these 300, however, are affiliated with a handful of national or international organizations, he said, without naming them.

The Teamsters union has been under investigation for several years. The government also is conducting a massive investigation of the International Longshoremen's Union.

Civiletti told the panel the Justice Department has stepped up its fight against organized crime, particularly in the area of "labor-management racketeering."

Although Civiletti said the strike force program against organized crime is "alive and well," almost all of nine strike force attorneys testifying told the Senate panel that labor racketeering is on the increase.

Peter D. Vaira, in charge of the Chicago office of the Organized Crime Strike, Force, said organized criminals are looking to huge union pension and benefit funds as a new source for corruption.

Another organized crime fighter, Robert C. Stewart of the Newark, N.J., and Buffalo, N.Y., Justice Department field offices, told the panel: "The unfortunate reality of today is that little or no progress has been made to control labor racketeering over the past 20 years, despite some rather good legislation."