Ochoa had campaigned in Colombia to assert his innocence

Drug kingpin Fabio Ochoa, 46, was found guilty in a Miami court on charges that he shipped an average of 30 tonnes of cocaine per month to the United States in the late 1990s.

Ochoa, who claimed he gave up trafficking after serving six years in jail in Colombia, now faces from 20 years to life in a US jail.

He is one of the most prominent Colombian drug suspects to stand trial in the US since the two countries resumed extraditions in 1997.

The BBC's Jeremy McDermott in Colombia says the US has been trying for years to get Ochoa, a founder of the notorious Medellin cartel, behind bars on US soil.

He's made a life and a career and a king's fortune by being very careful Ed Ryan, Prosecutor

Ochoa was flown to the US in 2001 after being arrested in Colombia in 1999 along with about 30 other alleged traffickers as part of Operation Millennium, which broke up a major cocaine trafficking ring.

During the 1980s, he was one of the top operators in the team of the infamous Pablo Escobar, supplier in its heyday of 80% of the US cocaine market.

Bugged telephones

Ochoa had waged a campaign in Colombia to deny he had resumed illegal drug trafficking after his release from prison.

"Yesterday I made a mistake. Today, I am innocent," he said on the billboards and on the internet.

Prosecutors had little evidence connecting Ochoa, 46, to the Bogota-based network led by Alejandro Bernal.

In a case with 1,500 hours of Colombian police tapes, Ochoa's voice was caught on only one three-hour segment in Bernal's bugged office June 16, 1999.

"He's made a life and a career and a king's fortune by being very careful," prosecutor Ed Ryan told jurors.

"People don't get to be at his level by making stupid mistakes."

Traffickers' testimony

The defence insisted Ochoa socialised with traffickers but did not return to the life he abandoned in 1990. They said it was not Ochoa's voice on the tapes from Bernal's office.

The strongest evidence against Ochoa came from Bernal and three other co-defendants, who co-operated with prosecutors in hopes of getting lighter sentences.

They said Ochoa attended key meetings and was set to receive profits on parts of two multi-ton cocaine shipments.

Defence lawyer Roy Black said the government was desperate to get its hands on a man it blames for smuggling so much cocaine into the US in the past.