HONG KONG, Jan 10 (Reuters) - A Hong Kong website that publishes material mainly related to anti-government protests in 2019 said its users' access had been blocked by the city's internet service providers (ISPs).

The website, HKChronicles, said it began receiving reports from Hong Kong-based users saying they were no longer able to access the site as of late Wednesday.

"After discussing and investigating with our supporters, we found that some ISPs of Hong Kong have deliberately dropped any connection to our servers, so that the user could not receive replies from our servers, resulting in an inability to access our content," chief editor Naomi Chan said in a statement.

The South China Morning Post, citing unnamed sources, said on Sunday that Hong Kong police had invoked the city's national security law for the first time to block HKChronicles.

The police force had started asking ISPs to halt access, citing Article 43 of the law, the newspaper reported.

"The police will not comment on specific cases," a Security Bureau spokeswoman said in an emailed response to a Reuters request for comment. "In conducting any operation, the police will act on the basis of actual circumstances and according to the law."

The Security Bureau said offences endangering national security include secession, subversion, organization and perpetration of terrorist activities and collusion with a foreign country or with external elements to endanger national security. The offences are punishable with up to life in jail, according to the security law.

"All relevant action will be taken strictly in accordance with the law," the spokeswoman added.

Under the disputed legislation imposed on the Chinese-ruled Asian financial hub in June, the police can request service providers to restrict access to electronic platforms or messages that could pose a threat to national security.

HKChronicles said that based on reports from users, the ISPs suspected of being involved in the blocking included Smartone , China Mobile Hong Kong, PCCW "and others". It did not elaborate.

China Mobile, Smartone, and PCCW did not respond to requests for comment.

The Hong Kong and Beijing governments say it is vital to plug holes in national security defences exposed by months of sometimes-violent anti-government and anti-China protests that rocked the global financial hub in 2019.

Hong Kong police arrested 53 people in dawn raids on democracy activists on Wednesday, in the biggest crackdown since China imposed the security law last year. The arrests have raised alarm that Hong Kong has taken a swift authoritarian turn.

"I think right now many users are being affected, but few websites are being affected. It seems like it's a technology test, to test the influence of blocking websites to the entire Hong Kong network," Chan told Reuters via the social media platform Telegram. (Reporting by Jessie Pang and Donny Kwok; Editing by Anne Marie Roantree, William Mallard and Bernadette Baum)