Locomotive fire at Newcastle blocks line

About 90 commuters stuck in a train near Newcastle have been evacuated via ladders and escorted across the tracks, after a fire in a freight train blocked the track.

The fire has been extinguished but the track for Sydney-bound trains remains closed.

Firies were called to Cardiff at about 5am on Monday after the locomotive engine burst into flames because of an engine oil spill, Fire & Rescue NSW spokesman told AAP.

Fire crews have extinguished the blaze, and the trapped commuters were rescued with ladders, the spokesman said.

The two drivers of the goods train were also evacuated and no injuries were reported, he said.

The freight train is blocking the main line to Sydney, with buses replacing trains between Hamilton and Fassifern, NSW TrainLink North tweeted.