An employee at the British Consulate in Hong Kong who was detained in mainland China has been released.

A spokeswoman at the Foreign and Commonwealth Office confirmed the release in a statement to the PA news agency.

She said: “We welcome the release of Simon Cheng and are delighted that he can be reunited with his family.

“We will continue to provide support to them.

READ MORE: Foreign Office ‘urgently’ seeking more information about detained embassy worker 

“Simon and his family have requested privacy and we would be grateful if this is respected.”

Public security authorities in Shenzhen said Mr Cheng was released as scheduled after 15 days of administrative detention.

Hong KongThousands of protesters march near Hong Kong harbour (AP)

The Luohu public security bureau in Shenzhen, the mainland city neighbouring Hong Kong, made the announcement on its Weibo microblog account.

Mr Cheng was detained for violating mainland Chinese law and “confessed to his illegal acts”, the statement said, without providing further details.

“Simon is released. Simon is safe,” Max Chung, a supporter of Mr Cheng told the Associated Press.

“We’ve just managed to talk to him over the phone,” he said, adding that Mr Cheng would answer any further questions, but did not say when.

READ MORE: Simon Cheng Man-kit given 15 days of administrative detention in China

Mr Cheng’s detention stoked tensions in Hong Kong, which has seen months of anti-government protests.

The Scottish Government trade and investment officer was hired locally and did not have a diplomatic passport.

He was detained after he left for a business trip to mainland China.