The son of a Canadian couple detained in China over spying allegations said Tuesday his parents did not attempt to obtain military secrets and have been caught instead by the increasingly tense relations between Ottawa and Beijing.

Simeon Garratt also said his parents, who have lived in China for 30 years, did not try to convert local Chinese to Christianity or send missionaries or converts into North Korea.

Garratt said the arrest of his parents, Kevin Garratt, 54, and Julia Dawn Garratt, 53, is "pretty absurd," because they have lived as open Christians in China for years without any trouble. The parents have run a coffee shop in Dandong, near the North Korea border, since 2008.