A staffer at the British Consulate General in Hong Kong has been detained in mainland China for more than 10 days, according to his girlfriend, who claims her beau urged her to pray for him when he crossed the border.

Simon Cheng Man-kit, a trade and investment officer at the Scottish Development International section of the consulate, passed through the Lo Wu control point to attend a business event in Shenzhen on Aug. 8, the Hong Kong Free Press reported.

He never returned to Hong Kong, even though he’d planned to head home that same day, his girlfriend told the outlet.

A spokesperson for the UK’s Foreign and Commonwealth Office said Tuesday that the reports about Cheng’s disappearance are troubling.

“We are extremely concerned by reports that a member of our team has been detained returning to Hong Kong from Shenzhen,” the spokesperson told the Free Press. “We are providing support to his family and seeking further information from authorities in Guangdong Province and Hong Kong.”

Cheng, a Hong Kong permanent resident, had studied in Taiwan and the UK before returning to the city, according to the report. It’s unclear whether he holds a diplomatic passport, and what materials he needed to provide to enter China.

The day Cheng embarked on his trip, he texted his Taiwanese girlfriend that he was on a high-speed train, “ready to pass through the boarder [sic],” according to a screenshot obtained by the outlet.

“Pray for me,” he reportedly added.

Cheng could have been detained at a joint checkpoint, located at the underground levels of the Express Rail Link’s West Kowloon Terminus, which is considered Chinese territory, according to the report.

But an officer from the station told Chinese-language publication HK01 — the first to report the story — that no arrests were made at the mainland Chinese police station of the West Kowloon Terminus on Aug. 8 or 9.

Cheng did not return to work on Aug. 9, the Free Press reported.

A unit at the Immigration Department, which aids Hong Kong residents outside the city, told Cheng’s girlfriend on Aug. 10 that he was under administrative detention in mainland China, but the reason and precise location were not known, according to the report.

Administrative detention in mainland China can last up to 15 days, the outlet reported.

Police told the paper that Cheng’s disappearance is being considered a “missing person” case.

An Immigration Department spokesperson said it was conferring with the Hong Kong Economic and Trade Office in Guangdong, at the request of one of Cheng’s relatives.

“[The department has] provided the family with proper advice and practical assistance,” said the department’s statement, obtained by the Free Press.

But Chinese Foreign Ministry spokesperson Geng Shuang said at a Tuesday press conference that he was unaware of Cheng’s disappearance.

Cheng’s disappearance comes as fiery pro-democracy protests have rattled Hong Kong — with many of the city’s residents accusing the Communist Party-ruled central government of increasingly eroding their freedoms.

Protesters have demanded the resignation of Hong Kong leader Carrie Lam, as well as democratic elections and an independent investigation into police abuse.