Police are investigating the circumstances of a serious single car crash in Mornington this morning which resulted in two people receiving critical injuries.

Around 7.30am police responded to a single car crash on the Tasman Highway at Mornington.

A red Holden Cruze had crashed into a tree around 500 metres from the Mornington roundabout, heading towards Hobart.

The driver of the car, a 21-year-old man from Acton Park, and the front seat passenger,a 19-year-old woman from Warrane, were both transported to the Royal Hobart Hospital in a critical condition.

The Tasman Highway was partially closed for around five hours.

Police are investigating the circumstances of the crash.

Anyone who witnessed the crash or the car prior to the crash is asked to phone police on 131 444 or Crime Stoppers anonymously on 1800 333 000.

Anyone with dash cam or smart phone vision of the crash or the car prior to the crash is asked to upload it direct to investigators via the Axon portal: https://taspol.au.evidence.com/axon/citizen/public/police-investigate-serious-mornington-crash