Police Search festival goers for drugs during Nimbin's Mardi Grass Festival.

A POLICE clampdown on cannabis smokers at Nimbin's annual Mardi Grass festival was allowing it to be taken over by amphetamine and alcohol use, an organiser said.

"The crowd are complaining there's not enough pot," Mardi Grass parade marshall Graeme Dunstan said of this weekend's festival.

"There's too much alcohol and too much speed, which people bring in from outside. The police go for cannabis because it's easy to spot."

Police have vowed to stamp out drugs in Nimbin. They sent officers from the riot, drug and mounted squads, plus regular officers, as an estimated 20,000 people gathered for a weekend of music, pot smoking and protest to demand the legalisation of cannabis.

"We are seeking to eliminate the supply of prohibited drugs," Richmond Local Area Command acting Superintendent Steve Clarke said on Friday. "We will not tolerate any breaches of any laws."

Michael Balderstone, president of the Nimbin Hemp Embassy, said the Nimbin community was furious about the police's approach. "You may as well get a stick and poke it in a hornet's nest. It's pointless. You can put us in jail for 20 years and you won't change our opinions."

Police obtained a court order on Friday to close the Nimbin Hemp Bar and Hemp Museum for 72 hours. Police alleged the bar and museum were known drug-dealing premises.

A raid on the museum on April 1 allegedly recovered four kilograms of cannabis. Eight people were charged with drug offences.

Mr Balderstone said the fact that only cannabis was found showed that Nimbin had got rid of its hard drugs problem. "We had ice [crystal methamphetamine] four or five years ago but the community's worked very hard to get ice out of town," he said.

Police were also enforcing alcohol-free zones at the festival, acting Superintendent Clarke said.

Debbie Guest, owner of the Nimbin Hotel, said the police clampdown had been "huge", with strict enforcement of responsible service of alcohol rules.

"We've never had trouble at Mardi Grass," she said. "People come for a good time."

Graham Way, 71, a Nimbin resident for 50 years, said the clampdown was a good thing. "You get harassed going up the street by people peddling drugs," he said.

Mardi Grass events include the Hemp Olympix, including a plantathlon, bong throwing and joint rolling.