Dutch dealer Willem van der Bijl is missing in North Korea.

The thematic dealer travelled to the secretive country on July 17, and was due to return on July 30. His family reported him missing on August 3.

The Netherlands does not have diplomatic links with North Korea, which does have an embassy in London. Diplomats are believed to have attempted to find out van der Bijl's whereabouts through the Netherlands' South Korean embassy.

South Korea news site Chosun Ilbo speculated that van der Bijl 'may have been arrested for trying to buy rare stamps from an individual North Korean'.

Van der Bijl was later shown on the website of The Pyongyang Times, the state-owned English-language newspaper, as the author of an article praising the North Korean election system.

The Utrecht-based dealer is a regular at Stampex with a large thematic stand.

His business partner, Ronald de Groen, said van der Bijl had visited North Korea dozens of times, and he had not expected to hear from him during his visit because mobile phones are confiscated at the border.

The pair also dealt in propaganda paintings.