Police are investigating a pedestrian crash in Launceston in which a man in his 70s was seriously injured.

A 74 year old man was struck by a Mercedes sedan travelling north on Invermay Road, Invermay in the vicinity of Goodman Court just after 5am today.

The man, who was on the roadway at the time he was struck, was transported by ambulance to the Launceston General Hospital where he remains in a serious but stable condition.

Police on patrol in the area witnessed the crash and provided immediate first aid to the man until Tasmania Ambulance Service arrived on scene.

Invermay Road was closed for two hours while Tasmania Police crash investigators and forensic members collected evidence from the scene.

The driver of the Mercedes submitted to mandatory drug and alcohol testing.

Inquiries are continuing but anyone who saw a gold/silver Mercedes sedan travelling on Invermay Road around 5am is asked to contact Tasmania Police on 131 444 and reference job number 20-30062023.