Melbourne train operator Metro Trains is calling on the industrial umpire to step in and stop another major public transport strike.

In what would be the city’s second transport strike in as many weeks, the Rail, Tram and Bus Union (RTBU) has announced plans for more industrial action.

Metro has submitted an application to the Fair Work Commission to suspend the planned industrial action.

The union says it will halt Melbourne public trains between 10am and 2pm on Friday, as the RTBU fights for the upper hand in wage negotiations.

Metro says the industrial action is unsafe.

“This week's planned industrial action poses a safety risk to the travelling public and our employees,” a Metro spokesperson told News Corp reporters.

“We are at an impasse so have escalated this to the industrial umpire.”

A hearing will take place this afternoon.

The RTBU says the on-and-off enterprise negotiations with Metro have been going on for six months with no breakthrough, so now frustrated members have no choice but to strike.

It follows a four-hour tram stoppage in the city last week, which caused widespread chaos and commuter complaints.

Public transport users said many of the promised replacement buses never came, and traffic on the roads ground to snail’s pace.

Reports say Metro Trains’ tram counterpart Yarra Trams’ last offer was for a pay rise of 15 per cent over four years, if staff agreed to work a 14-day roster.

The RTBU is allegedly demanding an 18 per cent pay rise over three years.