Hong Kong pop stars Kelvin Kwan and Jill Vidal have been arrested for possessing cannabis on a visit to Tokyo, a news report said Wednesday.

Kwan, 25, and Vidal, 26, were arrested in the Dogenzaka shopping centre in Shibuya, Tokyo, on February 24 when shopkeepers reported a foreign man trying to steal goods, the South China Morning Post said.

A police search found cannabis in a packet of cigarettes Kwan was carrying, according to the newspaper. Vidal reportedly denied any criminal behaviour.

The pair, who have taken part in anti-drug campaigns in Hong Kong schools, were arrested and face a maximum penalty of being barred from Japan and a jail sentence up to five years, the Post reported.

According to the newspaper, Kwan, who holds a Canadian passport, told police he had brought the cannabis with him from Hong Kong while Vidal, a British passport holder, said she knew nothing about the drugs.

Kwan and Vidal are among a host of young pop stars popular in China and Taiwan who sing so-called Canto-pop music produced by record labels in Hong Kong.