The operator of train systems in Hong Kong and Melbourne has been chosen to run the first privately operated passenger rail line in Sydney, the north-west rail link.

Premier Mike Baird and Transport Minister Gladys Berejiklian announced on Tuesday morning that MTR Corporation, along with John Holland, Leighton Contractors, UGL Rail Services and Plenary Group, had been chosen to operate the $8.3 billion train line.

The operator of Melbourne Metro Rail is coming to Sydney. Credit:Penny Stephens

In time, the private train operator will also run other parts of Sydney's train system.