Hong Kong activists are holding up blank signs because China now has the power to define pro-democracy slogans as terrorism

• Protesters in Hong Kong are holding up blank signs to dodge China's new national-security law, which was imposed on the city last week.
• The law gives China vast discretion to define and punish instances of "separatism, subversion, terrorism" in the city.
• For this reason, dozens of people gathered for a silent protest with white signs at malls around the city on Monday.
• Scroll down to see photos.

Hong Kong protesters are holding up white signs after China passed a new security law that gives them the power to label pro-democracy slogans as sedition or terrorism.

Photos showed around 200 people stood on balconies surrounding the central atrium of the APM mall in Kwun Tong district on Monday.

Other photos showed people taking part in a Monday lunchtime protest at the luxury IFC mall.

Most protesters held aloft white, blank sheets of paper, though some still carried signs bearing words and graphics.

One protester at IFC mall held up a sign bearing an anti-government slogans like: "Five demands, not one less," in a reference to demands made by pro-democracy activists last year; and "Carrie Lam, resign," in reference to the city's chief executive, who promulgated the law.

The IFC protest was silent, but riot police arrived after protesters began to chant "liberate Hong Kong," according to local media outlet RTHK.

Here's what the IFC mall protest looked like:

And here's what the APM mall protest looked like:

China passed the National Security Law for Hong Kong last Tuesday, despite opposition from the US, EU, and UK, and weeks of protest in the city.

The wording of the law is vague, but it essentially means that anything that China believes to be "separatism, subversion, terrorism" in Hong Kong can be punished under the law.

One protester at IFC, identified only as Tam, told RTHK that the white signs "show that there is a 'white terror' in Hong Kong."

Blank signs have been seen in other parts of Hong Kong too.

Hong Kong's libraries have also started removing books by pro-democracy activists from their shelves and catalogs.

Some campaigners have deleted their social media or even fled the city.

The UK has offered a path to citizenship for 3 million Hong Kongers in the wake of the national-security law. The US and Australia are also considering moves to help Hong Kong residents trying to flee.

• Read more:
• A Hong Kong protester was plucked from his Cathay Pacific flight to London and arrested on suspicion of stabbing a police officer
• Hong Kong pro-democracy campaigners are planning a 'parliament in exile' as activists delete their social media and flee China's new security law
• Boris Johnson offers 3 million Hong Kong citizens refuge in the UK in retaliation for China imposing national-security law
• Hong Kong schools have been ordered to display the Chinese flag and sing the Chinese national anthem as the city begins enforcing a controversial anthem law
• The US wants to kill part of an 8,000 mile-long undersea cable linking Hong Kong with LA over China spying fears