Police in California say they have destroyed nearly $US2 billion ($2.2 billion) worth of marijuana plants in the Sierra Nevada mountains.

The White House's Office of National Drug Control Policy director, Gil Kerlikowske, says the police found industrial-sized plantations of marijuana.

He says about 450 agents destroyed more than 432,000 marijuana plants during a clampdown that has lasted almost three weeks.

A total of 97 people have been arrested over the past three weeks, most of them Mexican nationals believed to have ties with Mexican drug cartels.

The move is part of an ongoing sweep of marijuana growing operations that has netted more than $US1.7 billion worth of the drug in the Sierra Nevada mountains.

- BBC