Premier Daniel Andrews has shot back at the union leader behind Thursday's Melbourne-wide tram strike after she publicly questioned whether his public transport minister was "out of her depth".

As many as 1500 tram drivers and staff walked off the job from 10am to 2pm on Thursday as part of their second strike to demand better pay and conditions.

Striking drivers outside the Malvern tram depot. Credit:Justin McManus

Speaking to 3AW on Thursday morning, Rail, Tram and Bus Union secretary Luba Grigorovitch ramped up the rhetoric with an attack on Public Transport Minister Melissa Horne for failing to resolve the union's long-running dispute with Yarra Trams.

“I don’t know if the minister is asleep at the wheel, I don’t know if she’s out of depth – I’m not sure what’s going on,” Ms Grigorovitch said.