Hong Kong (CNN) The family of a Hong Kong citizen working for the British consulate, who has not been heard from for more than two weeks, have described reports that he was detained in China for soliciting prostitutes as a "joke."

On Thursday, China's state-run tabloid Global Times reported that Cheng had been detained for "solicitation of prostitution." The report attributed the information to police in the Luohu district of the Chinese border city of Shenzhen, where Cheng had been traveling on business on August 8 in his role as a trade officer.

CNN has reached out to Luohu police who declined to comment.

But a Facebook page run by Cheng's family dismissed the report late Thursday. "Soliciting prostitution, everyone continues to see it as a joke," said the comment.

Cheng has been detained under a law that is often used as a preliminary measure to allow police to investigate a suspect before deciding whether to prosecute. In the past, China has been criticized for arresting dissidents and activists on trumped up charges, including sex crimes.

Cheng's friend Tommy Cheung, 25, told CNN that the charges were "nonsense." He described his friend -- who he has known for two years -- as"hardworking" and a "good person without any bad habits." Cheng's girlfriend Annie Li declined to comment on the charges Thursday.

Following the Global Times report, a British Foreign and Commonwealth Office spokesperson said they were urgently seeking further information about Cheng's case.

"Neither we nor Simon's family have been able to speak to him since his detention," the spokesperson told CNN on Thursday. "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."

Friends fear that Cheng's detention may in fact be linked to recent pro-democracy protests in Hong Kong.

Travelers to the border between Hong Kong and mainland China have told CNN that Chinese immigration officials are regularly searching travelers' phones and bags for evidence they have taken part in protests. Cheng's friends said he had shared pro-democracy images on social media and had voiced support for the city's ongoing protest movement.

Cheung said he hadn't seen his friend at the actual protests. When asked if his friend was afraid to go to the mainland, Cheung said most Hong Kong people are afraid of crossing the border because they don't believe China has rule of law.

Cheung said his friend's detention showed why people began protesting about the now-suspended bill that would allow extradition to China.

"It is justifying why we oppose the extradition bill," he said. "And it is justifying why people worry about the rule of law in China, because they have no rule of law in mainland China."

Cheng has not been heard from since August 8, when he messaged his girlfriend to tell her he was on a high-speed train, traveling from the Chinese city of Shenzhen to Hong Kong. "Pray for me," he texted her as he approached Chinese immigration, screenshots seen by CNN show.

The train between the two cities only passes through one immigration checkpoint: West Kowloon station , in Hong Kong. Thanks to a controversial deal agreed last year , parts of the station operate under Chinese law, allowing Chinese immigration officials and police to operate there. It was the first time such measures have been permitted in Hong Kong.

Since reports of Cheng's case broke, the Canadian Consulate in Hong Kong has suspended all work travel to mainland China for local staff. A government source who was close to the decision making said they believed the move to be a prudent precaution at this time.