The telephone belonging to a Norwegian student who disappeared in Amsterdam two weeks ago was ‘active’ on December 31, Dutch media reported at the weekend.

A foundation set up by three former police officers told local broadcaster ATV that research carried out abroad showed Tore Grodem’s Samsung Galaxy phone sent out a signal in the city two weeks after he vanished.

This report led to a major search operation in the city’s Vondel park at the weekend. Some 20 people, 15 dogs and a boat were involved in the hunt for Grodem, without success.

Grodem, 21, was last seen going round to the back of his hotel near the Leidseplein after being dropped off by an ambulance in the early hours of the morning on December 18.

The Simpar foundation was set up three months ago following the disappearance of two young Dutch women in Panama. It aims to provide extra expertise and help for families whose relatives disappear abroad.