International public relations firms rejected the Hong Kong government's appeal to help restore the city's reputation after months of pro-democracy protests, leader Carrie Lam said.

Ms Lam said the PR firms told the government that "the time is not right" as the violence and unrest in the semi-autonomous Chinese territory showed no signs of ending.

She did not give details on the firms or when they were approached.

The city's reputation was likely tarnished not just by the protests but by what many viewed as the government's slow response to the crisis.

Days after more than a million people took to the streets in early June, kicking off the protests, Ms Lam suspended an extradition bill that sparked the unrest but refused to formally withdraw it.

Continuing protests rock Hong Kong: In pictures Show all 35 1 /35 Continuing protests rock Hong Kong: In pictures Continuing protests rock Hong Kong: In pictures Police officers point their guns towards pro-democracy protesters after a clash at a march in Hong Kong on August 25 Reuters Continuing protests rock Hong Kong: In pictures Pro-democracy protesters throw molotov cocktails during clashes with riot police in Hong Kong on August 25 Reuters Continuing protests rock Hong Kong: In pictures Demonstrators rally behind barricades ass they are shrouded in tear gas deployed by police in Hong Kong on August 25 Reuters Continuing protests rock Hong Kong: In pictures Police clash withpro-democracy protesters at a march in Hong Kong on August 25 Reuters Continuing protests rock Hong Kong: In pictures A police officer prepares to strike a protester as clashes erupt during a pro-democracy march in Hong Kong on August 24 AFP/Getty Continuing protests rock Hong Kong: In pictures A water cannon is fired by riot police to clear the street of demonstrators during a protest in Hong Kong on August 25 EPA Continuing protests rock Hong Kong: In pictures Pro-democracy protesters use a slingshot during clashes with riot police in Hong Kong on August 25 Reuters Continuing protests rock Hong Kong: In pictures Riot police fire tear gas to disperse pro-democracy protesters in Hong Kong on August 24 Reuters Continuing protests rock Hong Kong: In pictures A demonstrator throws a molotov cocktail as they clash with riot police during a protest in Hong Kong on August 25 Reuters Continuing protests rock Hong Kong: In pictures A demonstrator swings a tennis racket in an attempt to knock back a tear gas cannister thrown by riot police during a protest in Hong Kong on August 25 Reuters Continuing protests rock Hong Kong: In pictures A protester displays a Hong Kong Independence flag during a pro-democracy march in Hong Kong on August 24 EPA Continuing protests rock Hong Kong: In pictures Riot police tend to a detained demonstrator who has been injured during a protest in Hong Kong on August 25 Reuters Continuing protests rock Hong Kong: In pictures A demonstrator uses bamboo poles to build a barricade during a protest in Hong Kong on August 25 Reuters Continuing protests rock Hong Kong: In pictures Riot police clash with demonstrators during a protest in Hong Kong on August 24 Reuters Continuing protests rock Hong Kong: In pictures Protesters are hit by tear gas fired by the police in Hong Kong on August 24 AFP/Getty Continuing protests rock Hong Kong: In pictures Demonstrators shrouded in tear gas shield themselves behind barricades during a clash with riot police in Hong Kong on August 25 Getty Continuing protests rock Hong Kong: In pictures Riot police arrest a protester during a pro-democracy march in Hong Kong on August 24 EPA Continuing protests rock Hong Kong: In pictures Police clash with pro-democracy protesters at the Hong Kong international airport on August 13 AFP/Getty Continuing protests rock Hong Kong: In pictures Protesters fall back as they clash with police during a protest at Kowloon Bay in Hong Kong on August 24 AFP/Getty Continuing protests rock Hong Kong: In pictures Police clash with pro-democracy protesters at the Hong Kong international airport on August 13 Reuters Continuing protests rock Hong Kong: In pictures Riot police move to disperse protesters during a clash at the Hong Kong international airport on August 13 Reuters Continuing protests rock Hong Kong: In pictures Commuters riding in a bus drive past protesters in Hong Kong's Kowloon Bay on August 24 AFP/Getty Continuing protests rock Hong Kong: In pictures Protester hold umbrellas as they take part in a pro-democracy march in Hong Kong on August 24 EPA Continuing protests rock Hong Kong: In pictures Riot police detain a demonstrator as they clash during a protest in Hong Kong on August 24 Reuters Continuing protests rock Hong Kong: In pictures Pro-democracy protesters block the entrance to the airport terminals after clashes with police at the Hong Kong international airport on August 13 AFP/Getty Continuing protests rock Hong Kong: In pictures Riot police spray pepper spray as shield themselves by a police van during a clash with pro-democracy protesters at the Hong Kong international airport on August 13 Reuters Continuing protests rock Hong Kong: In pictures Riot police use pepper spray to disperse protesters during a demonstration at the Hong Kong international airport on August 13 Reuters Continuing protests rock Hong Kong: In pictures Demonstrators shrouded in tear gas shield themselves behind barricades during a clash with riot police in Hong Kong on August 25 Reuters Continuing protests rock Hong Kong: In pictures Medical professionals gather to protest police brutality at the Queen Elizabeth Hospital in Hong Kong on August 13 Getty Images Continuing protests rock Hong Kong: In pictures Police detain a pro-democracy protester at the Hong Kong international airport on August 13 AFP/Getty Continuing protests rock Hong Kong: In pictures A protester is halted by police during an occupation at the Hong Kong international airport on August 13 AP Continuing protests rock Hong Kong: In pictures Police clash with pro-democracy protesters at the Hong Kong international airport on August 13 AFP/Getty Continuing protests rock Hong Kong: In pictures Police stand guard at the entrance of the departure terminals at the Hong Kong international airport on August 13 AFP/Getty Continuing protests rock Hong Kong: In pictures Protesters continue their occupation at the Hong Kong international airport on August 14 AP Continuing protests rock Hong Kong: In pictures Travellers read placards and posters left by pro-democracy protesters at the Hong Kong international airport on August 14 AP

She caved in this month after the demonstrations escalated, but the promise to ax the bill was deemed too little, too late as protesters widened their demands to include democratic reforms.

"It would perhaps be not the most cost-effective way to use government resources to launch any campaign to rebuild Hong Kong's reputation, but sooner or later, we will have to do it because I have every confidence in Hong Kong's fundamentals," Ms Lam told a news conference Tuesday.

"The time will come for us to launch a major campaign to restore some of the damage done to Hong Kong's reputation."

Hong Kong's economy, already reeling from the US-China trade war, is facing its first recession in years, with tourist arrivals plunging and businesses being hit by the unrest.

Violence flared again over the weekend after an unapproved march downtown descended into familiar chaos.

Ms Lam said the city's downgrade this week by credit ratings agency Moody's was "disappointing" but acknowledged that the continued instability has tarnished international perception of Hong Kong's financial stability.

Moody's was the second agency to make the move after Fitch Rating.

Ms Lam said that she will begin open dialogues next week with various community groups, including protesters, and that participants can freely express their views.

Many protesters have said the dialogues are meaningless if the government refuses to accept their four other demands: direct elections for the city's leaders, an independent inquiry into alleged police brutality, unconditional release of protesters who have been detained and not labelling the protests as riots.

The leader said not all Hong Kong citizens support the protesters' demands and reiterated that the government cannot condone violence.

She said the dialogues are not one-off "gimmicks" but an important first step to resolve grievances over problems such as shortage of affordable housing and lack of jobs that contributed to the unrest.

A subway train derailed during Tuesday morning rush hour, sparking rumours that it may have been caused by protesters, some of whom have vandalised subway stations in recent weeks.

Transport secretary Frank Chan urged the public not to speculate as investigations are ongoing.

The fire department said eight people were injured, with five of them hospitalised.

Associated Press