The first high-speed sleeper train from Hong Kong to Beijing departed on Saturday evening, with the transport minister calling the new overnight services a "breakthrough".

Secretary for Transport and Logistics Lam Sai-hung, who was onboard, also said the administration would look to see whether it was possible to increase the number of sleeper trains.

"Now we get four days of sleeper services. But it depends on how it goes. And I would say that if it is welcomed by the general public, we'll push for more," he told reporters prior to departure.

The train for Beijing left at 6.24 pm on Saturday, and passengers will arrive at their destination about half a day later.

"I'm very happy and excited that I can take the first train to Beijing. I haven't been to Beijing for a long while. I'll be able to see the bustle and the prosperity of our nation's capital," a lady surnamed Chung said.

"This train is really good. It is fast. I only need to sleep one night and then I will arrive when I wake up. It saves a lot of time."

China Travel Service was among the travel agencies allotted tickets for the trip. Its managing director, Chen Rui-dong, said all of its 35 tickets were quickly snapped up.

"Following the chief executive's announcement, the tickets were sold out in half a day. We hope that there will be more sleeper train services in future," he said.

Another sleeper train bound for Shanghai was set to depart from Hong Kong at 7.49 pm on Saturday.

Under the new regular services, which will have trains running between Friday and Monday, trips from Hong Kong's West Kowloon terminus will take about 12.5 hours to get to Beijing, and around 11 hours to Shanghai.