The UK Foreign Office has expressed concern over reports that a Hong Kong consulate employee has been detained at the Chinese border.
Media reports said Simon Cheng, who is thought to be from Hong Kong, is believed to have gone missing on 8 August.
An FCO statement said it was "seeking further information from authorities in Guangdong Province and Hong Kong".
The British embassy in Beijing is providing support to the family.
An FCO spokesperson said: "We are concerned by reports that a member of our team has been detained while returning to Hong Kong from Shenzhen."
Local outlet HKFP reports that Mr Cheng is a trade and investment officer at the Scottish Development International section of the consulate, and had travelled to a business event in Shenzhen on 8 August via the Lo Wu immigration control point.
His girlfriend told news site HK01 he had planned to travel home by train the same day, but did not return.