About 100 passengers have spent up to two hours stuck in Melbourne's city loop rail tunnel after a train breakdown.
Passengers had to be walked out of the tunnel by emergency services personnel, after the Frankston line train broke down when the device connecting it to overhead powerlines developed a fault between Melbourne Central and Parliament on Sunday afternoon.
Passengers, including six mobility impaired people, spent up to two hours stuck on the train as MFB crews rescued them.
A second train was also affected by the breakdown, leaving passengers stuck between Parliament and Richmond stations, Metro spokeswoman Larisa Tait said.
Those passengers were taken to Richmond station.
The trains remain stuck in the tunnel but Ms Tait said the morning peak should not be affected.
"We would be very confident that this will be cleared later this evening and it won't affect tomorrow morning's peak," she told AAP.
Trains on the Frankston, Pakenham, Cranbourne and Sandringham lines are running direct to Flinders St and are experiencing 20 minute delays.
Ms Tait said during the evacuation passengers on the Frankston train had to walk about 500m through the tunnel to Melbourne Central station.
"There is some space in there but there's not a lot, so it can be a delicate task," she said.
An Ambulance Victoria spokesperson said no-one was injured as a result of the incident but one person was taken to hospital with a medical condition.
