HONG KONG (NYTIMES) - The latest diplomatic incident between China and Sweden was born in, of all places, the lobby of a hostel.

Earlier this month, a Chinese man named Zeng and his parents arrived at the Generator hostel in Stockholm, the Swedish capital, the state-run media in China reported.

It was just after midnight, and he asked if his parents could wait in the lobby until check-in opened later that day.

But Mr Zeng said the hostel staff members called police officers, who forcibly removed the family and dropped them near a cemetery outside town, the state-run Global Times newspaper reported.

"I could not imagine this happening in any modern country, especially Sweden, the hometown of the Nobel Prize," he was quoted as saying by Global Times.

Over the weekend, nearly two weeks after the tourists' removal, the Chinese Embassy said in a statement that the three had been "brutally abused by the Swedish police".

The statement came a day after the embassy issued a safety alert for Chinese travellers in Sweden - one of the safest countries on earth.

The incident, which comes eight months after Chinese authorities detained Gui Minhai, a Hong Kong book publisher with Swedish citizenship, may further strain relations between the two countries.

In 2015, Gui became a symbol of the Chinese government's determination to smother criticism from abroad when he and four other Hong Kong booksellers disappeared and later resurfaced in China in police custody.

Gui, whose business sold gossipy books critical of China's leaders, was formally freed in 2017, but ordered to remain in China.

In February, more than two weeks after he was snatched from a Beijing-bound train, Gui resurfaced to say in a police-arranged interview that he wanted no help from the outside world.

But Sweden's Foreign Minister, Ms Margot Wallstrom, said that taking him from the train had been a "brutal intervention" and that China had contravened "basic international rules on consular support".

In 2012, Chinese tourists spent US$102 billion (S$139.83 billion) abroad, making them the world's biggest source market for international tourism.

They are an increasingly dominant spending force in Sweden and beyond, if also among the world's most resented travellers.

Out of about 4.7 million guest nights by international visitors in Stockholm County in 2016, Chinese nationals accounted for 117,476, a 74 per cent rise from 2011, according to data published by the Stockholm Business Region, a company owned by the city of Stockholm.

Most stayed in hotels, but 7,392 stayed in hostels.

Given all that, the Chinese Embassy's charge of "brutal abuse" levelled against Swedish police was clearly a diplomatic shot across the bow.

The embassy also said it was "deeply appalled and angered by what happened and strongly condemns" the behaviour of Swedish police.

"We urged the Swedish government to conduct thorough and immediate investigation, and respond to the Chinese citizens' requests for punishment, apology and compensation in time," it added.

"We cannot understand why the Swedish side has not given us any feedback."

Ms Linn Duvhammar, a spokeswoman for Sweden's Ministry of Foreign Affairs, acknowledged the request by the Chinese Embassy but said the case had been handled by "the responsible authority", referring to police.

Stockholm police spokesman Lars Bystrom said on Monday, "We have nothing more to say in this case."

Mr Karl Jigland, a press officer for the Swedish Prosecution Authority, said on Monday that the Public Prosecution Office determined that police had not committed a criminal offence during the incident at the Generator hostel and decided on Sept 7 not to open a preliminary investigation.

The prosecutor's office did not consider whether the police officers' actions were "the best way to handle a situation", he said, adding that such questions were handled by police themselves.

But police spokesman Bystrom said no such investigation was being conducted in this case.

A receptionist who answered the phone at the Generator in Stockholm on Monday said she had no comment.

The hostel is one of several Generator locations around Europe, and the company's website describes the hostels as "unique, stylish, experience and design-led spaces at affordable rates".

The Generator's rules say that customers who disturb guests or fail to "conduct themselves in a reasonable and responsible manner" may be asked to leave.

Global Times reported that Mr Zeng's father was dragged out first by police, and his wife fed him medicine as he lay on the ground.

Mr Zeng said it was at that point that he "lost his mind" and began yelling at police officers.

He recalled saying: "Help, the Swedish police is killing us!"

After being dropped by police near a cemetery outside the city, he said, the family waited for a half-hour until a passer-by stopped and gave them a ride back to Stockholm. He called the whole ordeal a "nightmare".

On Chinese social media, some users expressed anger over the family's ordeal, saying that the Swedish police's apparent behaviour was particularly insulting to older people.

But many others described the family's emotional reaction to their experience as a national disgrace for China.

One user wrote that Mr Zeng's outburst was a stunt that might work in China, but not Sweden, "a society ruled by law."

"I condemn this kind of unruly behaviour," another wrote. "It is shameful for the whole family and the whole country."

Still other users speculated that Global Times was publicising Mr Zeng's story as retaliation against Sweden for recently hosting the Dalai Lama, the exiled Tibetan spiritual leader, who has been accused by China of secretly advocating Tibetan independence.