By Noel Randewich

OAKLAND, California (Reuters) - Federal agents raided a cannabis cultivation college on Monday in the San Francisco Bay area widely known as the "Princeton of Pot" and the "Harvard of Hemp," authorities said, as the U.S. government pressed its clamp-down on medical marijuana.

Raids at Oaksterdam University in Oakland and other unspecified locations were carried out under a federal search warrant that was sealed by a judge, said Joycelyn Barnes, special agent for the U.S. Drug Enforcement Administration's San Francisco Division.

She confirmed that agents from the DEA were joined by personnel from the Internal Revenue Service and the U.S. Marshals Service in conducting the operation.

Barnes said no arrests were anticipated from the raids, which she said began early in the morning. But she declined to comment on the specifics of the sweep, what prompted it or what precisely federal agents were looking to find.

"This is just part of the three agencies combining resources to investigate criminality involving marijuana," she told Reuters. A federal marshal and an IRS agent on the scene at Oaksterdam University said only that a search warrant was being executed.

The raid followed a report in the Sacramento Bee newspaper last month that enrollment at the school has declined sharply since the federal government began a broad crackdown on medical marijuana dispensaries and cultivation facilities.

In California and other states that have legalized pot for medicinal reasons, the U.S. government has moved in recent months to shut down storefront medical cannabis shops and greenhouses deemed by federal investigators to be serving as fronts for drug-trafficking networks.

Oaksterdam, which offers courses in cannabis cultivation and related careers, holds classes on Wednesday mornings and one weekend every month.

Salwa Ibrahim, an executive assistant for Oaksterdam founder Richard Lee, said Lee's whereabouts were not immediately known, and declined to comment on the raid, except to say, "This whole thing is kind of a bummer."

Outside the school, the entrance of which was blocked off with yellow crime-scene tape, several dozen protesters stood holding signs. "End federal interference," one read. "Cannabis is medicine," read another.

One demonstrator, Michael Little Bear, a 50-year-old laborer on disability with a back injury, said he had taken a class called "Horticulture 102" at the university.

"I tried it (marijuana) and it worked. So the next step was I wanted to make it. There's goodness here. ... They teach the right way to do things," he said.

(Reporting by Noel Randewich; Writing by Steve Gorman; Editing by Cynthia Johnston and Todd Eastham)