Carmen Lau, 30, a pro-democracy activist and former councillor in Hong Kong, said she believes the letters, which are being investigated by the police, were the latest attempt by China to intimidate her.

Lau, like several other high-profile Hong Kong refugees in the UK, found out first earlier this year that her neighbours had been sent letters encouraging them to turn her in to the Chinese embassy, offering rewards of tens of thousands of pounds.

On November 11 Joshua Reynolds, her local MP for the town of Maidenhead, west of London, told her he had been informed by residents that "new letters had been placed on their doorsteps," Lau told AFP.

The envelopes bore a stamp from the Chinese region of Macau, she said.

AFP has not seen a copy of the letters.

"There are five images having my face on it and either they're naked or just wearing underwear and like, they are acting or signalling that I am a sex worker providing services," Lau said.

The letters also included personal information such as Lau's name, height, weight and a note that read like an advertisement for a sex worker, "kind of like welcoming people to come to my flat", she said.

"I was shocked and terrified, but at the same time, I was quite angry about it," she said in the telephone interview.

"Even till now I'm quite hesitant to head to the town because, you know, Maidenhead is such a small town, and I have no idea how widely the images were circulated, and how people would think."

She has since moved out of the property, as she did after the first set of letters, but she said the "psychological burden" was the worst thing.

She said it was "psychological warfare to stop us from what we've been doing".

In December 2024 Hong Kong police announced bounties of HK$1 million (around $130,000) for information leading to the arrest of Lau and five other activists based overseas and accused of national security crimes.

- 'Malicious communications' -

Political dissent in Hong Kong has been quashed since Beijing imposed a sweeping national security law in 2020.

Reynolds, who confirmed Lau's account, said "Beijing's efforts" to intimidate and threaten Hong Kongers like her are "utterly grotesque".

"The government cannot stick its head in the sand when it comes to the safety of Hong Kongers in our country," he told AFP.

"It must take decisive action to show we won't tolerate Beijing's campaign of international repression."

A spokesperson for the Chinese embassy in the UK dismissed the allegations.

"We have read the report," the spokesperson said. "The story sounds weird," he said, adding that it was only Lau's account.

A Thames Valley Police spokesperson said officers were investigating reports of a "malicious communications offence" involving "digitally altered images".

A UK government spokesperson said: "The safety and security of Hong Kongers in the United Kingdom is of the utmost importance."

"We encourage anyone to report concerns to the police."