A Dutch cyber security expert who went missing in Norway two weeks ago has been sighted in Denmark, Dutch police said on Thursday.

Arjen Kamphuis was last seen in the northern town of Bodo on August 20 and should have returned to the Netherlands on August 22 but he never arrived. On Monday a witness told police he had spotted the missing man in Denmark.

Police also say that Kamphuis’ mobile telephone had been turned on on August 30 in the vicinity of Vikeså, about 50k from Stavanger in Norway. The device remained active for 20 minutes after which a German sim card was put in it. It is not clear who did this, police said. Police are now investigating the data on the sim card.

The hunt for Arjen Kamphuis, 47, has been conducted by a police team known as Kripos, who specialise in organised crime and disappearances, Norwegian police said in a press release.

According to Dutch media he is an expert in cyber security who advises governments, journalists and human rights experts. He is also an associate of Wikileaks founder Julian Assange.