A 20-year-old man has died after being hit by an ambulance in Melbourne’s southeast.

Police say the Mercedes van struck the Frankston man on Cranbourne Road, Frankston, just before 2.30am on Monday.

The man was treated at the scene but died before he could be taken to hospital.

The ambulance was travelling with lights and sirens when the incident unfolded.

“Sadly the patient has passed away at the scene,” Ambulance Victoria said in a statement.

“We extend our deepest sympathy to the patient’s family.”

“A full investigation will be conducted into the circumstances of this tragic accident.”