Melbourne trains to be hit by strikes

Melbourne commuters have been warned to expect lengthy delays as train workers ramp up their fight for better pay and conditions.

Metro Trains staff have voted to take industrial action for the next two Mondays, the Victorian branch of the Rail, Tram and Bus Union says.

This is set to include work stoppages, a refusal to check tickets and staff leaving platform barriers open.

Metro Trains' chief executive, Raymond O'Flaherty, has warned commuters the action could lead to delays of up to an hour on Monday.

He also insists passengers will not be allowed to travel on the network for free.

"We want to get a new agreement in place as quickly as possible. We want to ramp up the pace of the negotiations," Mr O'Flaherty told reporters on Thursday.

Victoria's Rail, Tram and Bus Union branch secretary, Luba Grigorovitch, says her members have resorted to industrial action as a last resort after five months of negotiations.

The union had asked for a six per cent pay rise but its primary concern is ensuring workers secure better conditions, a spokesman told AAP.

It comes as Yarra Trams staff also vote to take industrial action.

This set to include bans on wearing uniforms, accepting rosters changes, voluntary overtime or last-minute timetable changes.