LONDON — The British government said it was "extremely concerned" over reports that an employee of its Hong Kong consulate has been detained.

The U.K. Foreign Office said on Tuesday that the employee had visited Shenzhen, a city in Guangdong Province in southeastern China, and was detained returning to Hong Kong.

“We are extremely concerned by reports that a member of our team has been detained returning to Hong Kong from Shenzhen," the statement said, adding that the foreign ministry was seeking further information from authorities.

A Scottish government spokesperson confirmed to NBC News that the employee is Simon Cheng Man-Kit, who works for Scottish Development International, based at the British Consulate in Hong Kong. A Linkedin page attributed to Cheng Man Kit says he has worked at the agency for 18 months.

The Scottish government said in a statement: "We are aware of this incident and we are concerned for Mr Cheng’s welfare. We are liaising with the FCO, who are in contact with Mr Cheng’s family, the authorities in Guangzhou and Hong Kong, and are seeking further information."

This incident follow months of protests against an extradition bill that Hong Kongers feared would eventually place Hong Kong under China’s jurisdiction. Those protests then turned into a wider pro-democracy movement which is calling for Hong Kong's historic rights, a legacy of its status as a former British colony, to be protected.

Hong Kong was returned to China in 1997 under the principle of "one country, two systems," which promises the region certain democratic rights not afforded to people on the mainland. In recent years, some Hong Kong residents have accused the Communist Party-ruled central government of steadily chipping away at their freedoms.

Tens of thousands braved heavy rain on Sunday in a show of the movement's ongoing enthusiasm.

Kong Wing-Cheung, senior superintendent of the Hong Kong police public relations branch, said in a press conference Tuesday that police had received a missing person's report on Aug. 9 but could not give more details.

The police had not received any notification from China under the reciprocal notification mechanism, he added. China's foreign ministry spokesperson, Geng Shuang, declined to comment on the reports on Tuesday.

The reports come as Hong Kong's leader, Chief Executive Carrie Lam, said Tuesday that she was setting up a "platform for dialogue" to resolve differences in the city following the protests.

Lam also said a fact-finding study will look at the causes of the protests and the police response to them.

Lam and other officials have conditioned dialogue on the protest movement remaining peaceful. Earlier protests have been marked by violence.