A police manhunt is under way for an escaped hospital patient after a woman in a Melbourne wellness centre had petrol and matches thrown at her in an attempted arson attack.

Investigators are looking for 25-year-old Ivanhoe man Bartholemew Griffith who absconded from the psychiatric unit at Heidelberg’s Austin Hospital on Saturday.

They warn people not to approach him but to call triple zero.

Police suspect he entered a Northcote wellness centre in an inner Melbourne suburb at 1.30am on Saturday, turned the gas on in the kitchen and fled.

He then allegedly returned at 2.50am with petrol, pushed past the 52-year-old female resident and doused the building before trying to ignite some paper.

The woman managed to lock a security door but was splashed with petrol and had matches thrown at her before her attacker fled.

The woman was temporarily staying at the premises and though she knew Mr Griffith, police don’t believe she was personally targeted in the attack.

Senior Constable Cameron Ashworth on Sunday implored members of the public who see Mr Griffith not to approach and to call triple zero immediately.

“We want help him to get the urgent care that he needs,” Senior Constable Ashworth told reporters.

“His behaviour is unpredictable. He is an involuntary patient of the psychiatric unit and we want to get him back there.”

He said an increased police presence would be seen around the Ivanhoe and Northcote areas, particularly the Darebin Parklands where Mr Griffith has previously slept rough.

-AAP