Customers were questioned by drugs squad officers as police raided a shop and cafe run by a cannabis campaigner.

Police equipped with bulletproof vests, helmets and battering rams rushed into the cafe and a strong smell of burning herbs and incense spread into the street.

More than 30 officers were involved and seized a substance believed to be herbal cannabis.

More than 20 customers were spoken to by officers during the raid at the Quantum Leaf cafe in the back room of Bongchuffa in Rowlands Road, Worthing.

The shop is run by Chris Baldwin, who stood as a Legalise Cannabis Alliance candidate in East Worthing and Shoreham in the last General Election.

Bongchuffa sells a variety of smoking paraphernalia, including pipes and cigarette papers.

Quantum Leaf is based on coffee shops in Amsterdam. A display cabinet with what looks like an array of different types of marijuana is fixed to a wall.

Police raided the property following complaints from nearby residents.

Inspector Allan Lowe, in charge of the raid, said the exercise had been successful.

He said: "It is important for public confidence in Worthing that we do take action of this kind.

"It is very important we are methodical and meticulous and that is what we are doing. No one in there is causing difficulties. We are making sure everyone is searched."

Mike Allday, who provides security at the coffee shop, said: "I provide personal protection for the owner because he is a disabled fellow and obviously a target. I also enforce the rules of no under-18s, no dealing and no alcohol.

"I think all this is unnecessary because it was a bit heavy-handed. We could have put bars on the windows but we have not done that. It's not that sort of place. We are not trying to do any harm."

Mr Baldwin was unavailable for comment.

A police spokesman said no one had been charged but 12 people had been arrested and were helping with inquiries.

He said a large quantity of cannabis had been recovered.