WASHINGTON (AP) _ Attorney General Dick Thornburgh today said 127 people have been charged in investigation he said smashed a billion-dollar international money-laundering ring with links to the Medellin drug cartel of Colombia.

Thornburgh called it ''the largest money-laundering crackdown ever carried out by the federal government.''

Authorities seized a half-ton of cocaine and $45 million in cash, jewelry and real estate, and have identified more assets for potential seizure, he said.

''There is no more effective way to deal with the business of drug trafficking than to take the profit out of it. That's what has happened with Operation Polar Cap,'' Thornburgh said at a news conference.

Federal authorities also obtained conspiracy indictments against two South American banks, Banco de Occidente of Panama and Banco de Occidente of Colombia, on charges they were involved in laundering more than $1 billion in drug proceeds generated in the United States.

Appearing with Thornburgh was FBI Director William Sessions, Drug Enforcement Administrator John Lawn and other federal authorities. Lawn said the sophisticated and complicated money-laundering operation laundered $1.2 billion in two years.

Thornburgh called it ''a very hostile takeover of a major money-laundering operation.''

Lawn said federal investigators in Atlanta were told by drug-world leaders that the money-laundering scheme they were operating undercover was processing the money too slowly and described a faster Los Angeles-based operation that could launder their money in 48 hours.

He said it was called ''La Mina,'' or ''The Mine,'' and that authorities began investigating that operation. He said it involved transfers of drug- proceeds and laundered money through several cities and Panama, Colombia and Uruguay.

The Justice Department said that among the indictments resulting from the investigation were charges against 29 people unsealed today in Atlanta and eight people arrested Tuesday evening in New York.

Bruce Pagel, an attorney in the department's narcotics section, said most of the 127 people charged in the investigation had been arrested but that authorities were still pursuing some.

The department said the Atlanta indictment traces the establishment of the money-laundering enterprise directly to leaders of the Colombian Medellin cartel, which authorities say is the source of 80 percent of the cocaine consumed in this country.

Federal agents were seizing accounts at banks in Atlanta, Miami, New York and San Francisco, and additional arrests were expected in New York, Los Angeles and Miami, the department said.

Thornburgh said there was no evidence of illegal activity by U.S. banks, and that the banks cooperated in the investigation.

Lawn said authorities also hoped to make an arrest today in Panama with the help of the Panamanian Defense Forces. Thornburgh said federal authorities continued to cooperate with the force, despite the pending federal drug indictment against Panamanian leader Manuel Noriega.