HONG KONG (Reuters) - Democracy protesters in Hong Kong were arrested Monday for ignoring a ban on masks and appeared in court Monday after deadly weekend clashes with police forces paralyzed high-speed trains.

Hong Kong Chief Executive Carrie Lam announced on Friday a ban on wearing masks during demonstrations, citing for the first time in 52 years the powers of emergency colonial powers.

The law authorizes executive authorities to "take any measures" without waiting for the green light from the legislature in case of emergency or if the population is in danger, provoking discontent and defying tens of thousands over the weekend by demonstrating masks.

Demonstrators outside the court chanted slogans such as "wearing the mask is not a crime" and "the law is unfair", expressing fears that it could lead to the adoption of new emergency measures.

Tens of thousands of Hong Kong residents took part in spontaneous rallies or peaceful marches throughout the city over the weekend, and police used tear gas to disperse them.

On Friday evening, extremist groups sabotaged several subway stations, government offices and institutions related to China, especially Chinese banks.

Three months ago, Hong Kong has been shaken by increasingly violent pro-democracy demonstrations. The protesters condemn Beijing's growing hegemony over Hong Kong's semi-autonomous domestic affairs and police actions.

The protest movement began in June against a bill allowing extradition of convicts to central authorities in Beijing. The project was abandoned in early September, but protesters raised their demands.