A Labour Tribunal has ordered STM maintenance employees to stop deliberately working slowly.

The ruling comes following hearings last week about the labour dispute involving STM maintenance workers during contract negotiations.

The Labour Tribunal said that the job action taken by workers -- namely deliberately working slowly -- is illegal.

The STM said the pressure tactics by maintenance workers has led to a severe increase in the number of buses in its fleet that are not roadworthy.

As a result buses are frequently not running at their scheduled hours on many routes on a daily basis, inconveniencing thousands of commuters.

Over the past year 30 percent of STM buses have been off the road, while in previous years only 20 percent of buses have been undergoing maintenance at any time.

Maintenance workers have been without a contract since January 2016, and have been in mediated talks since September 2018.

Earlier this week the STM extended what it called its final offer to maintenance workers.