Amsterdam police have arrested three people in their hunt for the killer of Reduan Bakkali, the brother of a crown witness who had given the police dozens of statements about the ongoing drugs war in Amsterdam.

A 41-year-old man was arrested in Hilversum on Friday night after a DNA match was found between traces left at the scene of the killing and DNA in the national forensic institute data bank, police said in a statement on Saturday.

A second man was arrested in Rijswijk on Friday night and a third was picked up in Westland on Saturday morning. These two men are suspected of possessing arms and involvement in the killing. Police have also seized several firearms, including automatic weapons.

The three men are being held in solitary confinement at Dutch  jails, which means they may only communicate with a lawyer.

Reduan Bakkali, 41, was shot dead at his marketing company offices in Amsterdam on Thursday by a man who had arranged a job interview with him.

The murder came within a week of the news that Nabil Bakkali was going to become a key witness. Bakkali was put in a witness protection programme in exchange for information on a number of murders related to Moroccan gang warfare.

Police confirmed on Friday that they have surveillance camera footage of the killer at the office where Reduan Bakkali was shot dead.