The Chinese government on Tuesday denounced those protesters in Hong Kong who stormed the city’s legislature as “extreme radicals”, and urged the police and government to hold them responsible.

The ministry of foreign affairs said the demonstrators had carried out “serious and illegal acts” that “trampled on the rule of law” during a daylong protest on Monday.

“We strongly condemn this behaviour,” Geng Shuang, a spokesman for the ministry, told reporters at a regular news conference in Beijing.

The remarks were a stern warning to protesters after weeks of demonstrations against a contentious bill that would allow extraditions to mainland China.

Those protests turned chaotic on Monday, when a small group of opponents to the bill stormed the legislature, ramming glass doors, destroying official portraits and spray-painting slogans in the inner chamber.

President Xi Jinping has emphasised the importance of maintaining the integrity of China’s territory and sought to expand Beijing’s influence in Hong Kong, a semi-autonomous territory. But the unrest in the former British colony has become an embarrassment for the party, which prides itself on the idea of a unified China.

Even as Xi’s patience is tested, experts said that the mainland was unlikely to take drastic action in Hong Kong, such as by deploying troops, and it would allow Hong Kong officials to address the tensions.

In a strongly worded statement, Beijing’s Hong Kong and Macau affairs office said that “some extreme radicals” used the extradition bill to justify attacking the legislative office building’s facilities.

The office called it a “blatant challenge” to the One Country, Two Systems policy under which the Chinese government is obliged to provide Hong Kong with a high degree of autonomy.

Several different government agencies, including the foreign ministry, also expressed firm support for the Hong Kong government and the police.

The mainland Chinese news media, which is tightly controlled by the ruling Communist Party, has provided little reporting on the protests that have roiled Hong Kong for the past several weeks and thrown the city’s leadership into a political crisis.

But on Tuesday, Chinese government statements criticising the protests received blanket coverage across major Chinese state media outlets alongside editorials that blamed the unrest on hostile western forces bent on fomenting a revolution in the territory.

The protesters were portrayed as hooligans motivated by mob violence, with state-run outlets omitting details of their broader political demands.

“Out of blind arrogance and rage, protesters showed a complete disregard for law and order,” said an editorial in the Global Times, a nationalist tabloid.

By limiting discussion of the protests, the government was obscuring a potential embarrassment to the party and Xi. The government also might be eager to prevent outbursts of nationalism, which can be seen as a challenge to party’s primacy, analysts said.

“The Party always wants to stay ahead of Chinese nationalism,” said Dan Lynch, a professor of Asian and international studies at the City University of Hong Kong.

The protests were a test of the Communist Party’s patience with Hong Kong, said Kerry Brown, a professor of Chinese politics at King’s College London. “They think, ‘we’ve allowed these people all these kinds of privileges and freedoms, and look at the way they behave,’” he said.

“It will just reinforce the narrative that this is a spoiled kind of place.”

With other pressing matters like a trade dispute with the US and a slowing economy, however, Professor Brown said Xi was likely to take a conservative approach, unless the unrest begins to inflict damage on Hong Kong’s economy.

Debris including umbrellas, hard hats and water bottles was among the few signs left of the mayhem that had engulfed parts of the city on Monday and overnight after protesters stormed and ransacked the Legislative Council, or mini-parliament.

Police cleared roads near the heart of the financial centre, paving the way for business to return to normal.

However, government offices, where protesters smashed computers and spray-painted “anti-extradition” and slurs against the police and government on chamber walls, were closed.

State news agency Xinhua wrote an upbeat Chinese-language report about a government-arranged concert in Hong Kong to celebrate the handover anniversary, complete with descriptions of the audience singing the national anthem and how the performers showed their “ardent love of the motherland”.