Tens of thousands of pro-democracy protesters filled the streets of Hong Kong late yesterday, stockpiling supplies and erecting makeshift barricades ahead of what some fear may be a push by police to clear the roads before Chinese National Day.

On the eve of today’s anniversary of the Communist Party’s foundation of the People’s Republic of China in 1949, crowds poured into central districts of the Asian financial hub, near where National Day festivities are scheduled to take place.

There was a carnival atmosphere among demonstrators, in contrast to weekend clashes when riot police fired pepper spray and tear gas to quell the unrest.

Nevertheless, rumours have spread among protesters that police could be preparing to move in again, as the pro-Beijing government, which has called the demonstrations illegal, vowed to go ahead with celebrations.

“Many powerful people from the mainland will come to Hong Kong. The Hong Kong government won’t want them to see this, so the police must do something,” Sui-ying Cheng, 18, a freshman at Hong Kong University’s School of Professional and Continuing Education, said of the National Day holiday.

“We are not scared. We will stay here tonight. Tonight is the most important.”

Online student groups urged supporters to move towards the convention centre, near the harbour waterfront, ahead of a planned flag-raising ceremony there this morning.

Student leaders had given Hong Kong leader Leung Chun-ying an ultimatum to come out and address the protesters before midnight yesterday, threatening to escalate action in the next few days to occupy more government facilities, buildings and public roads if he failed to do so.

The protesters, mostly students, are demanding full democracy and have called on Leung to step down after Beijing ruled a month ago that it would vet candidates wishing to run for Hong Kong’s leadership in 2017.

While Leung has said Beijing would not back down in the face of protests, he also said Hong Kong police would be able to maintain security without help from People’s Liberation Army (PLA) troops from the mainland.

In a blog post published shortly before the students’ deadline, Leung urged city residents to abandon the protest movement, widely known as “Occupy Central”, immediately.

“The impact on the value of Hong Kong’s international image is becoming greater and greater,” he wrote.

“I hope you will all think about this.”

Even though I may get arrested, I will stay until the last minute. We are fighting for our futures

People voiced concern that the protests could escalate today.

“I don’t know what the police or government will do to me, but I am 100 per cent sure I need to come out,” said Ken To, a 35-year-old manager of a restaurant in the densely packed Mong Kok residential district.

Its dark alleyways and triad-run bars – a far cry from the glittering high rises across the water for which Hong Kong is famous – could prove a flashpoint for violence, residents fear, although police have steered clear of the area in recent days.

China rules Hong Kong under a “one country, two systems” formula that accords the former British colony a degree of autonomy and freedoms not enjoyed in mainland China, with universal suffrage set as an eventual goal.

Protesters massed in at least four of Hong Kong’s busiest areas, including Admiralty, the Central business district, the bustling shopping district of Causeway Bay and Mong Kok in Kowloon.

Organisers said as many as 80,000 people thronged the streets after demonstrations flared on Friday night, and many have slept out for the past four nights blocking usually busy roads. No independent estimate of crowd numbers was available.

Alex Chow, leader of the Hong Kong Federation of Students, said the protests, which began as a gathering of students and the “Occupy Central” movement, had become much broader and attracted Hong Kongers of all walks of life. “It has evolved into a civil movement,” he said.

People set up supply stations with water bottles, fruit, crackers, disposable raincoats, towels, goggles, face masks and tents, indicating they were in for the long haul.

Some lugged metal road barricades into positions on the edge of crowds, presumably to slow a police advance.

In at least one location, several minivans and a truck were parked in rows in an apparent effort to block a road.

“Even though I may get arrested, I will stay until the last minute,” said 16-year-old John Choi. “We are fighting for our futures.”

The outside world has looked on warily, concerned that the clashes could spread and trigger a much harsher crackdown.

In Britain’s strongest interjection yet, finance chief George Osborne urged China to seek peace and said the former colony’s prosperity depended on freedom. Washington has urged the Hong Kong authorities “to exercise restraint and for protesters to express their views peacefully”.

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