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 could no longer access the site since Wednesday evening.

“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, the newspaper reported.

“The police will not comment on specific cases,” a Security Bureau spokesperson 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.”

Under the controversial legislation imposed on the Chinese-ruled city 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”.