The Foreign Office has said it is “urgently” seeking more information about a British Consulate worker detained in China.

Simon Cheng Man-kit, who works at the British Consulate-General in Hong Kong, was given 15 days of administrative detention after crossing the border on August 8.

A spokesman for the Foreign and Commonwealth Office said officials had been unable to contact Mr Cheng since.

He said: “We continue to urgently seek further information about Simon’s case. Neither we nor Simon’s family have been able to speak to him since his detention.

“That is our priority and we continue to raise Simon’s case repeatedly in China, Hong Kong and London, and have sought to make contact with Simon himself.”

China said Mr Cheng was detained in the city of Shenzhen for violating regulations on public order.

His detention comes after weeks of pro-democracy protests sparked by a now-suspended Bill which would have allowed extraditions from Hong Kong to China.

Tensions remain high as mass demonstrations continue, with protesters criticising both the Hong Kong and Chinese governments.

According to the Associated Press, Chinese Foreign Ministry spokesman Geng Shuang said at a daily briefing: “The relevant employee is a Hong Kong resident, not a British citizen.

“In other words, he is Chinese. This is purely the internal affairs of China.”

Mr Geng said Mr Cheng had violated regulations on “Punishments in Public Order and Security Administration”.