Thousands of democracy protesters have defied tear gas and police baton charges to remain on the streets of Hong Kong for another night amid rising international tensions.
Some demonstrators wore masks and resorted to umbrellas or plastic capes to protect themselves - prompting the phrase "umbrella revolution" to trend on social media.
However, in a shift of tactics, uniformed police looked on from behind barricades and have so far not intervened in the peaceful protest.
Sky's Asia Corespondent Mark Stone, at the scene, said the activists were "good natured but utterly driven".
Sunday night saw riot officers fire 87 rounds of tear gas after being charged by "violent protesters", with police saying 41 people had been injured.
The UK Foreign Office said it was "concerned" by the heavy response in its former colony - but China has warned the international community not to "interfere".
Chinese Foreign Ministry spokesman Hua Chunying said: "Hong Kong is China's Hong Kong. Hong Kong is purely our internal affair.
"We are resolutely opposed to any foreign country using any method to interfere in China's internal affairs."
Officials called on the activists to leave peacefully on Monday but thousands remained camped on a normally busy highway near government headquarters.
Organisers estimate as many as 80,000 people have taken to the streets since Friday.
Demonstrator Rick Chan described the chaotic scenes at the weekend.
He said: "I came last night and saw police fire many rounds of tear gas at the crowd, who were mostly young students and even included some old people."
An aerial drone captured lines of officers flanked by vehicles closing in on the crowd and firing gas cannisters.
Video from among the crowd captured the panic as coughing protesters ran for clean air.
With no imminent end in sight, China appears to have blocked photo-sharing site Instagram, suggesting authorities are worried about inspiring similar protests on the mainland.
Under the agreement of the 1997 handover from Britain to China, Hong Kong was given an independent legal and political framework.
Unlike the mainland, protests are allowed - but the current demonstrations are potentially the biggest political challenge to Beijing since the Tiananmen Square crackdown 25 years ago.
"The British government is concerned about the situation in Hong Kong and is monitoring events carefully," said a UK Foreign Office spokesman.