28-year-old Simon Cheng, who works as a commercial and investment officer for the British Consulate General in Hong Kong, was held in administrative detention for 15 days, Chinese Foreign Ministry spokesman Geng Shuang said Wednesday.
"I want to make it clear that this employee is a Hong Kong citizen, not a British citizen, so he's Chinese and this is a purely internal Chinese affair," said Geng.
Cheng told Li on the night of August 8, just before he crossed the border into Hong Kong, Li told CNN. She has not heard from him since.
"Simon has signed a deal with the British government," she told CNN. "If he had not been given this assignment, he would not have had to go to Shenzhen, and Britain must take responsibility for saving Simon."
General in Hong Kong said that employees arrested for work-related reasons received legal counsel.
"However, we need to clarify the facts before we can decide which action is appropriate," the spokesman said. "That's why we urgently ask for more information from the Chinese authorities about the imprisonment of Simon Cheng, and we stay in close contact with his family."
In a statement issued on Tuesday, the British Consulate General said it was "extremely worried". On August 8, Cheng Li said he was on the high-speed train. He later announced that he was about to cross the border, according to screenshots by CNN. If Cheng was on the high-speed train between Shenzhen and Hong Kong, the only immigration checkpoint is at West Kowloon Station. Parts of the broadcaster are subject to Chinese law, although it is located in Hong Kong, which is subject to a separate legal system from the mainland.
do not recognize dual nationality for a Chinese citizen, meaning that BNO passports are not recognized.
Cheng disappears as Hong Kong approaches its twelfth weekend with protests against democracy. Travelers told CNN that security at the Hong Kong-China border has increased since the demonstrations began in June.
A Hong Kong-born man who recently returned to the city from China told CNN that the border police seemingly randomly picked people to investigate them further. The man, who refused to be named, said the police had flipped through the photos on his cell phone.
On Wednesday, around a dozen people protested in front of the British consulate in Hong Kong to do more to help him. "Today could be Simon, tomorrow I could be," said a 29-year-old in the protest.
In a statement posted Wednesday morning, the family repeated that Cheng had been on a "business trip" to Shenzhen.
The family claimed to have received no notification of administrative detention, which was to be sent out within 24 hours of the detention of a person. "We simply never received documentation showing that Simon had been officially arrested by the authorities," the statement says.
In the statement, the family said that a lawyer representing her went to three detention centers in Shenzhen, but failed to find Cheng. Police stations in Shenzhen and Guangzhou and the Guangzhou Railway Public Security Bureau also had no information about his whereabouts.
The authorities in Hong Kong and mainland China, working on a separate legal system from Hong Kong, have published few details of the case. On Tuesday, senior Hong Kong police superintendent Kong Wing-cheung confirmed that they had received a report on missing persons on 9 August. The Hong Kong Immigration Department also confirmed that it had received a request for support from Cheng's family and provided word and deed
CNN contacted the Guangdong Provincial Public Security Bureau and the Shenzhen City Public Security Bureau.