A seven-year-old boy had part of his leg ripped off by a shark while swimming off the coast of French Polynesia.

The child was one of around 10 friends playing in the picturesque waters of Taiohae Bay on Nuka Hiva, the main island in the Marquesas archipelago, on Friday when the ocean predator struck.

The shark inflicted multiple bite wounds, ripping off one of his calves and leaving the boy with additional injuries to his right forearm and left hand, The Sun reported.

The boy was taken to the island's small hospital before being airlifted to the French Polynesia hospital center in Tahiti, around 1,500 kilometres (930 miles) from Nuku Hiva.

'I'm 35 years old and this is the first time I've seen this. These were long and deep wounds,' a firefighter who helped the child with serious bite wounds said.