Grass fires shut down Melbourne train line

A series of grass fires has shut down a train line in Melbourne, causing peak hour chaos.

Firefighters stopped trains on the Craigieburn line near Strathmore to extinguish a series of fires near the tracks on Tuesday morning.

Crews extinguished the fires in 40 minutes and they are not being treated as suspicious.

Metro trains says there are major delays of up to an hour on the Craigieburn line.

The Metropolitan Fire Brigade said the cause of the fire is currently unknown.