Crowds took their seats at Beijing’s Tiananmen Square on Tuesday for a huge military parade to celebrate 70 years of Communist Party rule, as a day of protest began to unfurl in seething Hong Kong.

Authorities in Beijing had closed roads, banned the flying of kites, and shut bars as they tightened security for an event marking China’s journey from a country broken by war and poverty to the world’s second-largest economy.

A phalanx of tanks and other military hardware will roll across Tiananmen Square under the gaze of President Xi Jinping, the country’s most powerful leader since Mao Zedong.

New weapons – including a hypersonic drone and an intercontinental ballistic missile whose range encompasses the United States – are expected to make their public debut, according to Paris-based analysts.

“Unity is iron and steel. Unity is a source of strength,” Xi said in a speech on Monday evening.

Communist Party grandees will watch as 15,000 soldiers march across Tiananmen, 580 pieces of military equipment are shown off and 160 aircraft roar overhead.

It will be followed by a pageant involving 100,000 civilians and 70 floats depicting China’s greatest achievements. Organisers will release 70,000 doves and 70,000 balloons before an evening performance and fireworks in Tiananmen.

“Beijing wants to highlight its military modernisation, political unity, and determination to protect its interests,” said Adam Ni, China researcher at Macquarie University in Sydney.

Crowds began to take their seats for the parade early on Tuesday but access was limited.

Authorities usually close factories to ensure blue skies during major events, but unhealthy smog covered the capital on Tuesday. (AFP)