His family had no news since early August. Simon Cheng, an employee of the British Consulate in Hong Kong, is being held in Shenzhen City for breaking public security law, Chinese Foreign Ministry spokesman Geng Shuang confirmed Wednesday (August 21st).

Mr. Geng did not specify exactly what facts were alleged against him or whether he would be released after being detained.

The latter pointed out that he was not of British nationality but Hong Kong, "that is to say, Chinese". "It is therefore entirely a Chinese domestic affair," said the spokesman.

The British Foreign Ministry said on Tuesday it was "extremely concerned" by reports of the arrest in China of an employee of his consulate.

His family, revealing the identity of the employee on Facebook, said that Simon Cheng went to Shenzhen, the neighboring Chinese city of Hong Kong, on August 8 for a business meeting. The family said they had lost contact with him in the evening while he was on his way home and was preparing to pass the customs checks to return to Hong Kong.

The case comes as relations between Beijing and London are tense by protests that have been going on for more than two months in the former British colony returned to China in 1997.

>> Read more: More than 100,000 protesters march through the streets of Hong Kong

With AFP