LOS ANGELES, NOV. 7 -- A federal jury has convicted three men on charges of cocaine trafficking and conspiracy in connection with discovery last year of 21.4 tons of cocaine in a suburban Los Angeles warehouse in the world's largest recorded drug seizure.

But after seven days of deliberation, the jury deadlocked Tuesday on verdicts for three other defendants, prompting U.S. District Judge Terry J. Hatter Jr. to declare a mistrial for the three.

Jurors said that they had been leaning 8 to 4 for conviction, and prosecutors said they would seek a new trial. The six defendants are to remain at a federal prison facility here.

The three who were convicted had given incriminating statements to Drug Enforcement Administration agents and local police after their arrest in September 1989. Their lawyers argued that the statements were coerced.

Convicted were Carlos Tapia-Ponce, 69, of Chihuahua, Mexico, a retired Mexican customs inspector, and two of his sons-in-law, James Romero McTague, 42, of El Paso, Tex., and and Jose Ignacio Monroy, 37.

Tapia was described by prosecutors as "the overseer {and} patriarch" of the drug-trafficking ring, who leased the warehouse. They estimated that more than 50 tons of cocaine was shipped from the warehouse to drug distributors nationwide before the operation was shut down.

Authorities found ledgers and notebooks in the warehouse and in El Paso indicating that the Colombian-produced cocaine was driven in big-rig trucks from El Paso to Los Angeles.