A former employee of the United Kingdom’s Hong Kong consulate has alleged that he was tortured by Chinese secret police while being detained across the border in August with officers questioning him over the UK’s role in the Hong Kong pro-democracy protests.

Simon Cheng, a 28-year-old Hong Kong citizen, was snatched up by Chinese authorities at the controversial West Kowloon station border point, located in the center of the former British colony, on August 8 after taking a train back to his home city following a business trip to Shenzhen.

During his 15 days in detention, Cheng writes in a lengthy Facebook post that he was held in solitary confinement, handcuffed, shackled, blindfolded, and hooded. At the detention center, he says that he was strapped into what is known as a “tiger chair” — a metal chair with bars to prevent a detainee from moving — not permitted to wear his glasses and not allowed to contact his family or a lawyer.

He also describes how he was forced into a van and driven 30 to 40 minutes away to an unknown location where he was subjected to more aggressive forms of what his interrogators called “training”:

I was hung (handcuffed and shackled) on a steep X-Cross doing a spread-eagled pose for hours after hours. I was forced to keep my hands up, so blood cannot be pumped up my arms. It felt extremely painful. Sometimes, they ordered me to do the “stress tests”, which includes extreme strength exercise such as “squat” and “chair pose” for countless hours. They beat me every time I failed to do so using something like sharpened batons. They also poked my vulnerable and shivering body parts, such as knee joint. I was blindfolded and hooded during the whole torture and interrogations, I sweated a lot, and felt exhausted, dizzy and suffocated.

Cheng says that between interrogation sessions, officers gave him political education lessons, telling him that China was not suitable for full democracy because the majority of the population was not well-educated, warning him about the dangers of populism, citing the treatment of Nicolaus Copernicus as one example.

He also says that he was subjected to sleep deprivation, forced to stand still for hours without moving. If he moved or fell asleep, he would be forced to sing the Chinese national anthem aloud as punishment.

Cheng worked as a trade and investment officer at the consulate and had been principally tasked with promoting Chinese investment opportunities in Scotland. However, he had recently been assigned with another mission of keeping tabs on the pro-democracy, anti-government demonstrations rocking the city.

For this task, Cheng, already a supporter of the movement, joined some of the social media groups that protesters used to coordinate their actions and talked personally with demonstrators. After breaking into his mobile phone by grabbing him by the hair and forcing him to use the phone’s facial recognition feature, Chinese officers printed out emails detailing the information about the protests that Cheng had passed on to the consulate, accusing him of being a British secret agent.

Cheng says that police threatened to charge him with armed “rebellion and rioting” if he did not cooperate, demanding to know what the UK was doing to fan the flames of the protest movement, asking him for information and confessions.

They started asking me if I know MI5 and MI6, anyone who seemingly work for both agencies, the building structure of the British Consulate-General Hong Kong, what floor for what departments and what the staff passes look like, etc. They were unhappy with the “question and answer” model, so requested that I proactively confess the “crimes I committed” regardless of what questions they ask. They expected I can complete their plot about “foreign meddling” in the Hong Kong protests. They expected me to confess 1.) UK instigates the riots in Hong Kong by donating money, materials and equipment; 2.) I organise, participate and incite the protest in violent way; 3.) I pay the bail, using my salary from UK government, for those mainlanders who were arrested by Hong Kong police.

While Cheng refused to confess to these serious accusations, he says that he was forced into recording two video confessions, one for “betraying the motherland” and another for “soliciting prostitution” — Cheng had paid a visit to a massage parlor after concluding business in Shenzhen.

Cheng says that his treatment began to improve as news of his disappearance made headlines around the world. In the end, he was released after 15 days — the standard time for administrative detention in China, a penalty that can be meted out without any sort of judicial oversight.

After returning to Hong Kong, Cheng soon fled, explaining that it has become too dangerous for him to live there. In November, he was asked to resign his post at the consulate, though he was reportedly offered support in the form of a two-year working visa in the UK.

However, in his Facebook post, Cheng complains that he is not receiving much in the way of “concrete support” from the UK government, adding that he is seeking asylum along with looking for work and study opportunities.

“I won’t give up the fight for human rights, peace, freedom and democracy for the rest of my life, no matter the danger, discrimination and retaliation I will face, and no matter how my reputation will be stained, and no matter whether my future would be blacklisted, labelled, and ruined,” he concludes.

Cheng’s description of his detainment echoes that of many other activists and dissidents who have been detained in China in the past. It has provoked outrage from the UK with British Foreign Secretary Dominic Raab summoning the Chinese ambassador.

“I summoned the Chinese ambassador to express our outrage at the brutal and disgraceful treatment of Simon in violation of China’s international obligations. I have made clear we expect the Chinese authorities to investigate and hold those responsible to account,” Raab said. “The FCO is working to support Simon and his fiancée, including to come to the UK.”

However, the Chinese foreign ministry has told the BBC that the Chinese ambassador would “definitely not” accept the summons — instead, the ministry has opted to summon the UK ambassador to China to “express their indignation.”

“We hope the UK will be prudent and stop interfering in Hong Kong and in China’s domestic affairs because it will, eventually, only harm the UK’s own interests,” added the ministry spokesperson.