In the anonymous letter, 350 executive officers working for the government said it’s shocking for Lam to say during the August 9 media briefing that some protesters have no stake in society.
They said they could not agree with it, saying every citizen is a stakeholder in society, regardless of who they are.
Showing staff cards with their names covered, the officers also accused the police of resorting to excessive violence when handling recent protests.
They said they would not rule out further industrial actions including a strike if the government refuses to back down.
In July, more than 230 civil servants from more than 40 bureaus and departments had issued an open letter to the government.
The civil servants, including some from RTHK, are also calling for an independent inquiry into the police’s use of force, and urge the government to introduce universal suffrage so that Hong Kong “becomes truly free and democratic”.