Two people have been killed after a Sydney to Melbourne express train derailed near the Victorian town of Wallan leaving some commuters trapped, officials say.

Several other passengers were being treated for injuries, emergency services said.

One person was airlifted to a hospital in Melbourne.

Images showed a number of twisted carriages had left the track, with one on its side. It is unclear what caused the train to derail.

The Australian Transport Safety Bureau confirmed that some of the 160 passengers on-board the interstate service had been injured, but couldn’t say how many.

The train was reportedly carrying nearly 200 people when it left the tracks at about 19:50 local time (08:50 GMT) on Thursday, some 45km (28 miles) north of Melbourne, the Victorian state capital.

It is understood to be the main long-distance service between Melbourne and Sydney.

This breaking news story is being updated and more details will be published shortly. Please refresh the page for the fullest version.