The two companies have 50-50 ownership in a new business called Casp (Clough-AMC subsea partnership) to be headquartered in Oslo with offices in Aberdeen, Houston and Perth.

"The new tie-up is the result of nine months of planning," said a Clough source. "Our commitment to building the first vessel was speculative. Moving ahead with the second unit hinged on securing this deal with Aker Marine."

Anne MŸrer, president of Aker Marine Contractors, said: "Establishing Casp enables us to reach the global market, which is needed with the two specialised vessels Boa DeepC I and Boa DeepC II."