Authorities were reacting to the publication of 18 advertisements in 13 international newspapers between August 19 and 20 as part of a campaign launched by two groups of protesters, one of which had carried out a similar campaign in June.
The media outlets which carried the full-page advertisements include the US-based New York Times, Germany's Allgemeine, Spain's El Mundo and France's Le Monde, according to Efe news.
The local government, which alleged that the campaign sought to "defame" Hong Kong, said the claims made in the ads were a "gross exaggeration aimed at presenting a misleading image of the city".
The government refuted the allegation that the rights and freedoms of Hong Kong residents were under threat and said the freedom of protest and press were "alive and kicking", adding that the police had allowed 100 out of the 125 protests planned since June.
The statement said that the city had been "seriously affected" by violent protests carried out by "a group of agitators" who were engaged in destroying the "very foundations" of the city and attacking anyone who disagreed with them.
This description is completely different from the one offered in the ad campaign, in which protesters urged readers to "Catch Hong Kong as we fall" and help them be heard around the world, calling the protests "The last stand for freedom".
"Amid tear gas and rubber bullets, this once vibrant and safe metropolis is at a crossroads", the open letter from the activists read.
"Since the protests against the controversial extradition bill started in June, Hong Kong's autonomy and freedom have been eroded beyond recognition.
"This is the ugly truth that the Hong Kong government does not want you to know: Hong Kong is becoming a police state," the ads said.
The Hong Kong protests, which started in June, were initially called to challenge an extradition bill presented by local authorities which would have allowed the deportation of suspects to mainland China, despite the absence of a treaty, a move which was seen by dissidents as an end to the judicial freedom enjoyed by the city.
Though the bill has been declared "dead" by the city's top leader Carrie Lam, the civil campaign against it has since morphed into a broader movement seeking democratic reforms in the Chinese special autonomous region and ultimately opposing Beijing's authoritarian rule.
According to the handover deal between London and Beijing, the "one country, two systems" formula - which includes certain freedoms for Hong Kong not recognized in mainland China - must be preserved until 2047.
( With inputs from IANS )