The Ministry of Foreign Affairs on Friday criticized violence during recent protests in the Hong Kong Special Administrative Region, saying it tainted the city's image, seriously challenged the rule of law and jeopardized the city's security, stability and public order.

At a news briefing in Beijing, ministry spokeswoman Hua Chunying also decried attempts of the city's nongovernmental Civil Human Rights Front to suggest 61 foreign countries and regions issue travel alerts for Hong Kong.

Such attempts are by nature colluding with foreign forces to interfere in China's internal affairs, Hua said. She reiterated that any such interference is intolerable.

Hua's statements came on the same day thousands of black-clad protesters occupied the arrival hall at Hong Kong International Airport, the world's eighth-busiest airport, to stage a massive sit-in protest against the now-suspended extradition amendment bill. Aside from chanting slogans attacking the SAR government, protesters also distributed flyers inside the airport.

Hong Kong is at a risk for another violent protest on Saturday. A planned rally, in response to attacks at Yuen Long metro station on July 21, when white-clad people assaulted commuters and passersby indiscriminately, was rejected by the city's police. However, there is concern that protesters will gather anyway.

Ireland had changed its travel status for Hong Kong to advise a "high degree of caution", while Singapore, Japan and South Korea called on its citizens to avoid areas where public gatherings are taking place and to follow local authorities' advice.

The HKSAR's Chief Secretary for Administration Matthew Cheung Kin-chung warned against taking part in the Saturday rally, as those joining in might be arrested for illegal assembly, punishable by heavy fines and imprisonment. "Whether there will be a procession or not, we cannot rule out the possibility of a large number of people turning up.… But we sincerely wish that the participants would never resort to violence when expressing their discontent and pay due respect to the public order and people's life in Yuen Long," Cheung said.

Different sectors also appealed to the public, especially to young people, not to participate in any illegal assembly and never turn to violence.

Many principals of middle schools and university heads signed statements calling for students to avoid the Yuen Long protest.

The Chinese General Chamber of Commerce called on all sectors to clearly draw the line with violent protesters to protect the rule of law.

According to the Public Order Ordinance, any person who convenes, holds, organizes, forms or collects an illegal assembly, or assists or is concerned in doing so, will face the maximum penalty of a HK$5,000 ($640) fine and imprisonment for five years.