The operation was preceded by the arrest in the past two weeks of a dozen drug dealers who were selling ecstasy in the San Antonio district of Ibiza, the haunt of many young British visitors, where the police had recently installed closed circuit television cameras. Ibiza clubs such as Privilege, which is described as “the world’s biggest club”, Amnesia, Es Paradis, Eden, Pacha and Space attract thousands of young British clubbers during the summer, often with special nights hosted by British DJs or clubs. Drugs are formally banned by most clubs but ecstasy is considered to be the Ibiza clubber’s favourite drug.

The island’s drug scene has been linked to the March 11 train bombings in Madrid, which killed 191 people. The mainly Moroccan Islamist bombers who blew up four morning commuter trains financed their operations and the purchase of dynamite with drug money. One of them was Jamal Ahmidan, a known drug trafficker who blew himself up, together with a police officer and six other radical Islamists, when they were surrounded by the police a few weeks after the attacks. Ahmidan had travelled to Ibiza the week before the attacks, apparently to close a trafficking deal. One of his contacts in Ibiza was recently arrested by the judge investigating the Madrid bombings.

The British magazine Mixmag, which is devoted to clubs and dance, reported in a recent edition that Ibiza was coming under pressure from underworld gangs. “If you take drugs in Ibiza this summer, you deserve to know what your money is paying for,” the article said. “More club tourists means more gangsters to supply their drugs, more drug-related crime and more clubbers going to jail than ever.”

Several years ago the British vice-consul on the island, Michael Birkett, resigned, claiming he was increasingly being forced to deal with British “degenerates”. An estimated half a million British people visit Ibiza every year. Some of the local drug trade is reported to be in the hands of British groups.