The use of a life size hologram of a suspect in a cold case sex attack resulted in 300 tips to a police hotline, and 40 men have been invited to take a voluntary DNA test, police have confirmed.

The hologram was shown on television at the end of last year and also displayed to passersby in shopping centres in Schiedam and Vlaardingen in an effort to track him down.

Police hoped the unorthodox approach will lead them to identify the man who attacked three girls in the storage areas of flats in Schiedam and Vlaardingen, raping two of them in the late summer over 11 years ago.

The rapist, whom police think is local, approached the girls when they were putting their bikes away in the cellar and threatened them with a knife. One girl was able to escape.

Following tips from the public, the police say they have identified 40 men who fit the description and have asked them all to undergo a voluntary dna test.

The list was drawn up based on objective criteria such as where they lived at the time, and a distinctive voice, police say.