The discovery of a soundproofed torture chamber believed to have been used by a narcotics gang should remind recreational cocaine users of the consequences of their habits, a Dutch public prosecutor has said.

Koos Plooij told a court in Amsterdam that the violence of the drug trade was a “repulsive, but apparently unavoidable” result of the widespread use of illegal drugs in the Netherlands and its neighbouring countries.

“The question is how many people are willing to admit that there is indeed a connection between their cocaine use – whether it is to party, deal with work stress or suppress psychological problems – and the underworld that is happy to answer demand but according to its own rules: corrupting, undermining, tough, sparing nothing and nobody,” Plooij said.

The comments were made at the latest hearing in the case of 11 suspects, including an alleged ringleader known as Roger “Piet Costa” P, who are accused of planning to murder rivals at an apparent torture site in Wouwse Plantage in Brabant.

Two years ago, police officers, acting on intercepted messages, discovered seven shipping containers in Wouwse Plantage in Brabant, six of which were allegedly used as cells containing handcuffs and legcuffs.

In the seventh container was a refashioned dentist’s chair, with straps for tying arms and legs, finger clamps, scalpels, claw hammers, pliers, loppers, pruning shears, gas burners, tie wraps and duct tape. The container was sound proofed.

Officers also found a freezer large enough to hold more than one person and a mortar mixing tub which was allegedly going to be used for waterboarding victims.

The court heard that a second site in Rotterdam was the operating base for an “arrest team” whose task was to pick up their intended targets and take them to the site in Wouwse Plantage.

Prosecutors provided the court with an intercepted message from the suspect known as Piet Costa in which he wrote, “There are a few now and I hope I get the chance to torture them”.

A second man, who is terminally ill and not currently on trial, allegedly wrote: “If they don’t cooperate, right in the knee”.

The court heard that the wives and children of the alleged gang’s rivals were also in danger of being targeted and “detained under the most barbaric conditions”.

In both sites, officer found stolen police uniforms, bulletproof vests and blue flashing lights.

Prosecutors called for a 12-year jail sentence for Roger P, known as Piet Costa, who is already facing a jail sentence of 17 years and nine months sentence over a separate conviction. He has been described as a major figure in the drug world.

The prosecution said there was nothing to substantiate the claims made by one of the suspects that they believed the containers were being set up for the purposes of growing hemp.

The suspects deny the charges.