Melbourne train operator Metro has apologised for poor communications with customers during major delays yesterday.

Commuters were delayed for more than two hours on the Belgrave, Lilydale and Alamein lines after a bat came into contact with powerlines, causing a short circuit.

Metro's Daniel Hoare says it was unacceptable that passengers were given incorrect information about the disruptions.

"I can reassure you that customer communications is now an extremely big focus for us," he said.

"It is one of our key areas of focus this year, we have to improve it.

"It's not acceptable to tell somebody there is a half hour delay and have them stuck on a train for two hours."

Services have returned to normal.