Sydney train services have been disrupted during peak hour after a freight train carriage caught fire.

Trains between Fairfield and Liverpool on the T2 and T5 lines, and between Villawood and Liverpool on the T3 line, were not running on Wednesday afternoon, Transport for NSW said.

The freight train locomotive caught fire on the roof near the driver’s cabin near Warwick Farm.

7NEWS chopper footage shows emergency crews working to extinguish flames on the freight train carriage, with smoke billowing from the engine.

Replacement buses had been requested but were not yet running at the time of the update.

Commuters are advised to delay travel, use alternative transport, and allow extra travel time.