Thousands of protesters blocked roads and public transport links to Hong Kong's airport on Sunday in a bid to draw global attention to their fight for greater democracy for the Chinese-ruled special administrative region, which is facing its biggest political crisis in decades.

Planes were taking off and landing, with delays, but trains were suspended and approach roads to the airport impassable as protesters erected barricades and overturned trolleys at the airport and in the nearby new town of Tung Chung.

Some passengers were forced to walk the last bit of their journey to the airport on foot, dragging their luggage behind them.

The MTR subway station in Tung Chung was closed and demonstrators used metal poles to smash CCTV cameras and lamps and dismantled station turnstiles. Police appeared to be running in all directions and made several arrests.

Protesters try to block the highway leading to Hong Kong International Airport. (Kai Pfaffenbach/Reuters)

Chek Lap Kok, built around a tiny outlying island in the dying days of British colonial rule, is one of the world's busiest and most efficient airports, reached by a series of bridges which were packed with traffic.

"If we disrupt the airport, more foreigners will read the news about Hong Kong," said one 20-year-old protester, asking not to be named.

Watch: CBC's Adrienne Arsenault reports from Hong Kong about the violent subway scene:

CBC's Adrienne Arsenault reports from Hong Kong on news that police beat train passengers on Saturday. 2:05

Black-clad demonstrators targeted the airport three weeks ago, jamming the terminal in sometimes violent clashes with police and prompting some flights to be cancelled or delayed.

Police said protesters hurled iron poles, bricks and rocks onto the railway track near the airport station and trespassed on the track. By early evening protesters in the immediate vicinity of the airport had left, but protesters in Tung Chung remained.

Difficulty leaving airport

"We have no idea how to leave. We're stuck," a masked protester said, as others looked for buses and ferries to get back home.

Sunday's demonstration comes after police and protesters clashed overnight in some of the most intense violence since unrest erupted more than three months ago over concerns Beijing is eroding the autonomy granted to the territory for 50 years when it was handed back to China in 1997.

Protesters gather on the freeway as travellers wheel and carry their luggage down a an empty road near Hong Kong International Airport on Sunday. (Chris McGrath/Getty Images)

China denies the charge of meddling and says the protests in Hong Kong are an internal affair. It has denounced the protests and warned of the damage to the economy.

Tourist numbers have plummeted in recent weeks and international trade fairs have been cancelled as the region faces its first recession in a decade.

China is eager to quell the unrest before the 70th anniversary of the founding of the People's Republic of China on Oct. 1. It has accused foreign powers, particularly the United States and Britain, of fomenting the unrest.

Several hundred demonstrators also gathered outside the British consulate in central Hong Kong, waving Union Jack flags and chanting "God save the Queen."

Subway violence

Parts of the MTR system ground to a halt as skirmishes spread to the subway on Saturday, with television showing images of people being beaten as they cowered on the floor behind umbrellas. Police said they arrested 63 people aged between 13 and 36.

Passengers try to get to the airport as anti-extradition bill protesters block the highway leading to it. (Tyrone Siu/Reuters )

Amnesty International said the subway violence should be investigated.

"Violence directed at police on Saturday is no excuse for officers to go on the rampage elsewhere," it said.

Watch: Joshua Wong talks about the arrests of fellow activists:

Pro-democracy activist Joshua Wong says Hong Kong is becoming a police state as authorities continue to crack down on protests. 1:04

The latest protests came on the fifth anniversary of China's decision to curtail democratic reforms and rule out universal suffrage in Hong Kong.

The unrest began in mid-June, fuelled by anger over a now-suspended extradition bill that would have allowed people arrested in Hong Kong to be sent to China for trial in courts controlled by the Communist Party.

But the turmoil has evolved over 13 weeks to become a widespread demand for greater democracy.

The unrest poses the gravest challenge to Chinese President Xi Jinping since he took power in 2012.

Protesters have called for a general strike on Monday, but it was not immediately clear who would take part.