The prominent Hong Kong student activist Joshua Wong was released from prison on Monday and immediately vowed to join the protest movement against a controversial Beijing-backed change to extradition laws.

Mr Wong, 22, had been convicted of contempt in relation to his activities leading the 2014 Umbrella Movement protests, which blocked major roads and shut down parts of Hong Kong for 79 days.

His release after serving five weeks of a two-month sentence comes amid a fresh political crisis, with demonstrators demanding the resignation of the city’s chief executive Carrie Lam.

Ms Lam again postponed the extradition bill at the weekend, after it triggered some of the most violent clashes between protesters and police in decades.

The bill would make it easier for Hong Kong to extradite suspects to many countries including mainland China. Critics say it will allow Beijing to abduct dissidents for show trials, undermining Hong Kong’s autonomy.

Hong Kong: Extradition law protests continue into second week Show all 40 1 /40 Hong Kong: Extradition law protests continue into second week Hong Kong: Extradition law protests continue into second week A reported two million people took to the streets to protest against a controversial extradition law in Hong Kong on June 16 AFP/Getty Hong Kong: Extradition law protests continue into second week Protesters part to allow an ambulance to pass through during a protest on June 16 that reportedly attracted two million people AFP/Getty Hong Kong: Extradition law protests continue into second week A protester pays tribute to a man who died after falling from a scaffolding during the protests against against the extradition law proposal on June 17 Reuters Hong Kong: Extradition law protests continue into second week Following the demonstration, protesters cleared rubbish from the roads where a reported two million people had marched AP Hong Kong: Extradition law protests continue into second week Protesters part to allow buses to pass through during a protest on June 16 that reportedly attracted two million people Getty Hong Kong: Extradition law protests continue into second week A riot police officer strikes at protesters during a protest against the extradition law proposal outside the Legislative Council of Hong Kong on June 12 Reuters Hong Kong: Extradition law protests continue into second week A police officer fires tear gas at protesters during a protest against the extradition law proposal outside the Legislative Council of Hong Kong on June 12 Reuters Hong Kong: Extradition law protests continue into second week Protesters scatter as police fire tear gas during a protest against the extradition law proposal outside the Legislative Council of Hong Kong on June 12 Pauline Leung via Reuters Hong Kong: Extradition law protests continue into second week Protesters carry a banner opposing the extradition law proposal outside the Legislative Council of Hong Kong on June 16 AP Hong Kong: Extradition law protests continue into second week A protester holds a picture of an injured man who later died after falling from a scaffolding during the protests against against the extradition law proposal on June 17 Reuters Hong Kong: Extradition law protests continue into second week Protesters run after police fire tear gas during a protest against the extradition law proposal outside the Legislative Council of Hong Kong on June 12 AFP/Getty Hong Kong: Extradition law protests continue into second week A protester rests after facing water cannons fired by police during a protest against the extradition law proposal outside the Legislative Council of Hong Kong on June 12 Reuters Hong Kong: Extradition law protests continue into second week Police officers use a water canon on a lone protestor near the Legislative Council in Hong Kong on June 12 AFP/Getty Hong Kong: Extradition law protests continue into second week Protesters gather outside the Legislative Council in Hong Kong on June 12 AP Hong Kong: Extradition law protests continue into second week A protester waves a British flag outside the Legislative Council in Hong Kong on June 12 Getty Images Hong Kong: Extradition law protests continue into second week Protesters leap over barricades as they occupy roads by the Legislative Council in Hong Kong on June 12 AFP/Getty Hong Kong: Extradition law protests continue into second week Some protesters run after police fire tear gas during a protest against the extradition law proposal outside the Legislative Council of Hong Kong on June 12 AFP/Getty Hong Kong: Extradition law protests continue into second week Police officers use pepper spray against protesters during clashes after a rally against the extradition law proposal on June 10 AP Hong Kong: Extradition law protests continue into second week A protester sits down in front of riot police during a protest against the extradition law proposal on June 12 Reuters Hong Kong: Extradition law protests continue into second week Protesters sit in a demonstration following violence in the previous day of protests on June 13 Reuters Hong Kong: Extradition law protests continue into second week Protesters barricade themselves in an area outside the Hong Kong Legislative Council during clashes with police after a rally against the extradition law proposal in Hong Kong on June 10 AFP/Getty Hong Kong: Extradition law protests continue into second week A bloody-faced police officer is led away by a colleague after clashing with protesters in a rally against the extradition law proposal on June 10 AP Hong Kong: Extradition law protests continue into second week Protesters march through Hong Kong in opposition to the extradition law proposal on June 9 AFP/Getty Hong Kong: Extradition law protests continue into second week A protester sits in front of a riot police line during clashes between protesters and police following a protest in Hong Kong in opposition to the extradition law proposal on June 10 AFP/Getty Hong Kong: Extradition law protests continue into second week Protesters march through Hong Kong in opposition to the extradition law proposal on June 9 EPA Hong Kong: Extradition law protests continue into second week A protester lifts a barricade while a police officer charges in with his baton during clashes after a rally against the extradition law proposal in Hong Kong AFP/Getty Hong Kong: Extradition law protests continue into second week A protester is arrested during a clash after a rally against the extradition law proposal in Hong Kong on June 10 Getty Hong Kong: Extradition law protests continue into second week Protesters hold pictures of Hong Kong Chief Executive Carrie Lam during a rally against the extradition law proposal in Hong Kong on June 9 AP Hong Kong: Extradition law protests continue into second week A protester wave a Union Flag in front of police officers during a protest against the extradition law proposal in Hong Kong on June 10 Reuters Hong Kong: Extradition law protests continue into second week Protesters gather outside the Hong Kong Legislative Council during a rally against the extradition law proposal in Hong Kong on June 10 AFP/Getty Hong Kong: Extradition law protests continue into second week A protester is grabbed by a policeman as he crosses the police line during a rally against the extradition law proposal in Hong Kong on June 10 AP Hong Kong: Extradition law protests continue into second week Protesters gather outside the Hong Kong Legislative Council during a rally against the extradition law proposal in Hong Kong on June 10 AFP/Getty Hong Kong: Extradition law protests continue into second week A police officer detains a demonstrator during a protest to demand authorities scrap a proposed extradition bill with China, in Hong Kong, China June 9, 2019. REUTERS/Thomas Peter Reuters Hong Kong: Extradition law protests continue into second week Police officers detain a demonstrator during a protest during a rally against the extradition law proposal in Hong Kong on June 10 AP Hong Kong: Extradition law protests continue into second week A protester shouts next to police officers during a protest during a rally against the extradition law proposal in Hong Kong on June 10 AP Hong Kong: Extradition law protests continue into second week Protesters march through Hong Kong in opposition to the extradition law proposal on June 9 AP Hong Kong: Extradition law protests continue into second week Police officers detain a demonstrator during a protest during a rally against the extradition law proposal in Hong Kong on June 10 Reuters Hong Kong: Extradition law protests continue into second week Police officers detain a demonstrator during a protest during a rally against the extradition law proposal in Hong Kong on June 10 Reuters Hong Kong: Extradition law protests continue into second week Protesters gather in a park in Hong Kong opposition to the extradition law proposal on June 9 Reuters Hong Kong: Extradition law protests continue into second week A protester sits by ramshackle barriers after clashes between protesters and police following a protest in Hong Kong in opposition to the extradition law proposal on June 10 AP

After leaving prison, Mr Wong laid flowers at a makeshift memorial outside a shopping mall where a protester fell to his death on Saturday night.

He tweeted: “Hello world and hello freedom. GO HONG KONG!! Withdraw the extradition bill. Carrie Lam step down. Drop all political persecutions.”

And speaking to journalists who mobbed him as he left prison, Mr Wong said he fully endorsed the protests against the extradition bill.

“I will join to fight against this evil law,” he said. Asked about the pressure on the chief executive, he said: “I believe this is the time for her, Carrie Lam the liar, to step down.”

Protest organisers said almost 2 million people turned out on Sunday to demand that Ms Lam resign, in what is becoming the most significant challenge to China’s relationship with the territory since it was handed back by Britain 22 years ago.

The mass rally, which police said drew 338,000 participants at its peak, forced Ms Lam to apologise over her plans to push through the extradition bill that would allow people to be sent to mainland China to face trial.

But on Monday, protest leaders said they would not accept the apology unless a set of demands were met, including the withdrawal of the bill, the release of arrested students, for officials to stop describing Wednesday’s rally as a riot, and for Ms Lam to step down.

Hong Kong opposition politicians echoed the calls for both Ms Lam and the proposed law to go.

“Her government cannot be an effective government, and will have much, much, much difficulties to carry on,” veteran Democratic Party legislator James To told government-funded broadcaster RTHK.

“I believe the central people’s government [in China] will accept her resignation.”

However, the official China Daily newspaper said Beijing’s leaders would continue to back Ms Lam, and lashed out at foreign “meddling” in the crisis.

Its editorial said China’s support for Ms Lam will “not waver, not in the face of street violence nor the ill-intentioned interventions of foreign governments”.

Ms Lam has delayed the bill but it has yet to be completely shelved.

“We cannot accept her apology, it doesn’t remove all our threats,” said social worker Brian Chau, one of several hundred protesters who stayed overnight in the Admiralty district around the government headquarters and legislature.

Some demonstrators cleared rubbish left after the vast but peaceful march while others sang “Hallelujah”, a gospel song that has become the unofficial anthem of protesters against Ms Lam.

The government headquarters will stay closed on Monday, officials said. A group of uniformed police stood by without riot gear, in contrast to their appearance during recent skirmishes with protesters.