BEIJING, June 4 -- High-speed sleeper trains linking Beijing and Shanghai with Hong Kong will commence operations on June 15, facilitating personnel exchanges between the Chinese mainland and Hong Kong, the China State Railway Group Co., Ltd. (China Railway) said on Tuesday.

Non-high-speed train services between Beijing, Shanghai and Hong Kong will be upgraded and replaced by high-speed services, after which passengers will be able to travel between the Chinese mainland and Hong Kong overnight.

The time it takes to travel between Beijing and Hong Kong will be reduced to about 12 hours, and the travel time between Shanghai and Hong Kong to about 11 hours, the operator has said.

The new services will run between Beijing West Railway Station, Shanghai Hongqiao Railway Station and Hong Kong's West Kowloon Station. Ticket sales for the high-speed sleeper trains will open on Wednesday, China Railway said.