China Oilfield Services Ltd (COSL) confirmed the charter cancellation in a regulatory filing to the Hong Kong Stock exchange.

Statoil said it had decided to cancel the contract for the COSL Pioneer some 13 months before the expiry of its charter in August 2016.

"COSL Pioneer has been suspended since 8 October 2014 and Statoil has not managed to find alternative activity for the rig during the intervening period," it said.

"We