BERLIN (Reuters) - German police detained a 29-year-old man suspected of trading narcotic drugs internationally over the internet through anonymous websites and sending them by mail to customers in Germany, police said on Wednesday.

In cooperation with Dutch authorities, police seized 400,000 euros (355,345 pounds) and 75 kg (165 lb) of ecstasy, marijuana, cocaine, amphetamine and heroin at the apartments of the suspect and at his mother in the Netherlands.

The dealer and his partners, using the pseudonyms “Mr. Drug Commander” and “Drugs Squad”, were receiving orders mostly from German customers on black market websites such as “Hansa Market” and “Dream Market”, federal criminal police said.

The man, who was not identified, was arrested on Nov. 9 while entering Germany to mail 34 shipments of drugs. A day earlier, in Ingolstadt in Bavaria, police had arrested a man who had ordered marijuana and amphetamines.

Dutch authorities are still looking for other gang members.

Police said online drug shops are boosting drug consumption and trafficking, requiring a shift in approach by German authorities.

“The supposedly anonymous ordering on the Internet motivates more young people to buy, consume or even sell drugs for profit,” said federal criminal police in a statement.

Police said the investigation began in August, leading to the initial arrest in October of six people in the Bavarian town of Coburg, which in turn helped identified 12 other buyers.

German customs police in July said they expected far more cocaine to flood into Europe in the future, and had seized nearly five tonnes of the drug in northern sea ports so far this year, more than three times their total in 2016.