The activist, who went into self-imposed exile last year, earlier announced on social media that he will give a speech at the summit on December 10.
In a statement posted on the Security Bureau’s website, Tang called Law’s behavior “despicable” and accused him of “betraying Hong Kong”, saying he had jumped bail and fled the city after being charged with illegal assembly.
The security minister alleged that Law had made many speeches in the past inciting hatred for the central and SAR governments.
“[The anti-China] Law intends to attend what the United States plotted as an anti-China conference disguised as something democratic. He is there to spread political lies and make comments slandering the central and SAR governments,” Tang wrote, adding that he feels “extremely furious” about the matter.
The security chief also accused the activist of violating local election laws as well as the national security law, for calling on people to “ignore” this month’s Legislative Council elections.