Melbourne music festival slammed in the wake of several drug overdoses

Rave organisers and health officials are facing criticism for failing to warn attendees of nine MDMA overdoses at the Hardmission music festival in Melbourne.

Eight of those overdosed were put into induced comas with three remaining in critical condition.

Two have since been discharged from hospital as their condition has become stable.

The state opposition says an emergency drug warning should have been issued as the crisis escalated on Saturday night.

A bill introduced by the Greens to implement pill testing is expected to be debated in state parliament later this month.