HONG KONG (REUTERS) - Hong Kong police arrested at least three protesters on the anniversary of pro-democracy demonstrations in 2019 that rocked the financial hub and eventually led to Beijing introducing a security law which critics say has stifled dissent.

The protesters were arrested for disorderly conduct and failing to produce proof of identity, while at least 10 people were summoned for violating a ban on gatherings, the police said, after protests in the Kowloon district of Mongkok and the chanting of slogans in breach of a national security law imposed last June.

Some people blocked roads by placing rubbish bins and other objects in them, the police said.

"The police strongly condemn protectors' acts endangering public health and safety," the police said in a post on Facebook, shortly before midnight on Saturday (June 12).

The three people arrested were male age 15 to 19, the police said.

Small groups gathered on Saturday to commemorate the first major clashes between protesters and the police two years ago when tens of thousands demonstrated against a proposed law for the former British colony that would have allowed criminal suspects to be extradited to the mainland for trial.

Many Hong Kong residents saw the proposed law as further erosion of the city's special status that was supposed to be guaranteed under a "one country, two systems" formula agreed when Britain handed it over to China in 1997.

The 2019 protests snowballed over subsequent months into a mass movement for democracy that included regular clashes between protesters and the police firing tear gas and rubber bullets.

The police deployed 2,000 officers around the city on Saturday, the South China Morning Post reported.

The police said on the eve of the anniversary that they had arrested two people on suspicion of promoting and inciting others to join an unlawful assembly. Activist group Student Politicism said two of its leaders were arrested.

There was no sign of any protests on Sunday.