A man is in a critical condition after suffering a nasty fall at a wharf in Westport, in the South Island, last night.

Emergency services were called to Kennedy St about 8.40pm where it was reported a man had fallen from a truck onto a boat below - a fall of about 13m.

He suffered serious head and hip injuries and paramedics were required to stabilise the man at the scene before he was taken to Nelson Hospital.

A southern ambulance communications spokesman said it was thought the man, in his 40s, may have been helping to unload items from the truck when he fell.