Ineos has confirmed plans to order additional vessels to transport shale gas-derived U.S. ethane to Europe.

The Swiss-based group said the additional supply would help secure the future of its Grangemouth site in Scotland, which it had threatened to close at the height of a labor dispute last autumn.

The multi-gas carriers ordered from Evergas - now six instead of the originally planned four - are currently being built in China. They will enter service in 2015, transporting product from the Texas Gulf Coast to Grangemouth and Rafnes, Norway, where Ineos is building terminals.