NEW YORK (AP) _ The district attorney's office bought a Chinatown clothing factory, used undercover police to run it and determined that organized crime has a stranglehold on the garment industry, The New York Times reported today.

The police, who supervised 25 garment workers in the noisy loft factory, found that mob-affiliated trucking companies were shaking down clothing manufacturers.

The investigators gathered evidence against two organized crime families, the newspaper said. No charges have been filed, but authorities said evidence will be presented to a grand jury.

''The evidence we have so far turned up shows that organized crime has a monopolistic stranglehold over trucking companies and the truckers are the lifeblood of the city's garment industry,'' Manhattan District Attorney Robert M. Morgenthau told the Times.

Threats and extortion demands by trucking representatives were secretly recorded during the set-up, unidentified investigators told the newspaper.

The trucking employees told the undercover agents which trucker would have the sole right to move their goods, the newspaper said. Prices were not negotiable.

If the company used another trucking company, it would still have to pay the one designated by the organized crime figures, the Times said.

Records of 10 garment district truckers were seized Jan. 30. Unidentified officials said seven of the 10 are controlled by Thomas Gambino, who has been identified by law enforcement officials as a captain in the Gambino crime family, and that two of the others are affiliated with figures in the Lucchese crime family.

Thomas Gambino's attorney, Michael Rosen, said suggestions that Gambino was connected to criminal activity were ''hysterical accusations by people in law enforcement who have to justify their existence,'' the Times said.

Thomas Gambino, 60, is the son of the late Carlo Gambino, reputed founder of the crime family that bears his name. The Gambino organization is said to be the most powerful organized crime group in the nation. Law enforcement officials believe it is now headed by John Gotti.

Thomas Gambino is married to Catherine Lucchese, the daughter of the late Thomas Lucchese, who is said to have founded the Lucchese crime family.

The district attorney's office paid $25,000 for the garment contracting company in Chinatown with sewing machines and other equipment, said Michael G. Cherkasky, an assistant district attorney in charge of the inquiry.

The company, which operated for most of last year, sewed skirts and jeans and delivered them to jobbers or manufacturers who provided the fabric. The firm lost $10,000 last year.

The firm's business was run by six state police officers. State investigators were used instead of city police officers to reduce the chances that an undercover agent would be recognized, Cherkasky said.

Cherkasky said he expected a grand jury will hear evidence of extortion, price-fixing and racketeering in several months.