On Tuesday evening Ines Wong gathered seven pieces of cardboard, attached to them colourful sticky labels with messages demanding the Hong Kong government retract a controversial extradition bill, and placed the notes under a busy footbridge in Kowloon Bay.

There, dozens of passersby helped themselves to the labels, wrote their own messages and put those on the “Lennon wall”, a form of protest inspired by anti-communist activists in 1980s Prague.

Quick guide What are the Hong Kong protests about? Show Hide Why are people protesting? The protests were triggered by a controversial bill that would have allowed extraditions to mainland China, where the Communist party controls the courts, but have since evolved into a broader pro-democracy movement. Public anger – fuelled by the aggressive tactics used by the police against demonstrators – has collided with years of frustration over worsening inequality and the cost of living in one of the world's most expensive, densely populated cities. The protest movement was given fresh impetus on 21 July when gangs of men attacked protesters and commuters at a mass transit station – while authorities seemingly did little to intervene. Underlying the movement is a push for full democracy in the city, whose leader is chosen by a committee dominated by a pro-Beijing establishment rather than by direct elections.

Protesters have vowed to keep their movement going until their core demands are met, such as the resignation of the city’s leader, Carrie Lam, an independent inquiry into police tactics, an amnesty for those arrested and a permanent withdrawal of the bill. Lam announced on 4 September that she was withdrawing the bill. Why were people so angry about the extradition bill? Beijing’s influence over Hong Kong has grown in recent years, as activists have been jailed and pro-democracy lawmakers disqualified from running or holding office. Independent booksellers have disappeared from the city, before reappearing in mainland China facing charges. Under the terms of the agreement by which the former British colony was returned to Chinese control in 1997, the semi-autonomous region was meant to maintain a “high degree of autonomy” through an independent judiciary, a free press and an open market economy, a framework known as “one country, two systems”. The extradition bill was seen as an attempt to undermine this and to give Beijing the ability to try pro-democracy activists under the judicial system of the mainland. How have the authorities responded? Beijing has issued increasingly shrill condemnations but has left it to the city's semi-autonomous government to deal with the situation. Meanwhile police have violently clashed directly with protesters, repeatedly firing teargas and rubber bullets. Beijing has ramped up its accusations that foreign countries are “fanning the fire” of unrest in the city. China’s top diplomat Yang Jiechi has ordered the US to “immediately stop interfering in Hong Kong affairs in any form”. Lily Kuo and Verna Yu in Hong Kong

“Before, we have occupied roads and held rallies but we were told we were in the way of other people doing business,” said Wong, 24, who works as a florist. “So this is the most peaceful, unobstructive, way to express ourselves. It is not in anyone’s way.”

After a turbulent month of protests and rallies joined by millions to fight against a proposed law that would allow individuals to be extradited to stand trial in China’s courts, more “Lennon walls” have emerged across the city this week, including in some unlikely suburban neighbourhoods such as the politically conservative Tai Po, Sha Tin and Tsuen Wan districts in the New Territories.

Hong Kong's Lennon walls - in pictures Read more

The walls have their roots in the 2014 civil disobedience “umbrella movement”, when protesters decorated the wall next to a staircase near the legislature building with colourful collages of sticky labels of support and encouragement to each other.

The Lennon wall was inspired by the original graffiti-decorated wall in Prague dedicated to John Lennon; by the late 1980s it had become a source of irritation for the communist regime on account of its many critical messages.

Facebook Twitter Pinterest A girl pastes a sticky label on a Lennon wall at a pedestrian bridge. Photograph: How Hwee Young/EPA

To keep up the spirit of the anti-extradition bill campaign, Hong Kong protesters have now created “Lennon walls” on any available space, including on pillars outside underground railway stations, in underground tunnels,and on footbridges.

“We Hong Kongers never give up!”, “The Hong Kong spirit will never die!” , “Where there is suppression there is resistance!” say some of the messages across the city.

Many protesters who are unsure about their next step say the messages are a way of showing that they will continue the fight. They have been experimenting with creative ways of demonstrating against the extradition bill and demanding democracy. But the hours-long occupation of the tax office and immigration buildings last month proved to be unpopular with citizens.

“Only when the messages are everywhere would people know we are still here,” said a young man who had helped create a Lennon wall on a footbridge in downtown Causeway Bay. “It’s a way of expressing ourselves under an authoritarian regime.”

The wave of protests which started on 9 June forced the government to suspend the bill and Hong Kong’s leader, Carrie Lam, said this week that the legislation was effectively “dead”. But the protesters were not reassured by her personal promise, which they said was no guarantee that the bill would not be revived later.

Facebook Twitter Pinterest One of the Lennon walls in Hong Kong. Photograph: Philip Fong/AFP/Getty

They continue to demand that the government fully withdraws the bill, releases all those arrested in protests and launches an independent investigation into police use of teargas, rubber bullets and truncheons on largely peaceful crowds.

The emergence of Lennon walls across the city came a week after the storming and vandalising of the parliament building on 1 July, also the anniversary of Hong Kong’s 1997 return to Chinese rule. The government has strongly condemned the protesters’ actions.

Claudia Mo, a pro-democracy lawmaker, said the Lennon walls, which she viewed as installation art, were “the best outlets for our young to vent the anger and resentment in a peaceful manner” and were “effective reminders of the governance crisis”.

But even this mild form of protest has attracted the ire of government supporters and stirred unease among the authorities. Local media reported that on Wednesday morning more than 200 police officers, some armed with shields, descended on a Lennon wall in Tai Po, where some messages supposedly exposed some police officers’ personal details.

Around the same time a man punched two people guarding a Lennon wall in a pedestrian walkway in Kowloon Bay , and later that night hundreds staged a noisy rally outside the Yau Tong underground station in Kowloon late after several students guarding a local Lennon wall were assaulted by unknown attackers. At one point during the impromptu rally people swiftly passed round sticky labels, wrote on them and stuck them on to nearby pillars.