The European Union on Tuesday raised the stakes in its battle with Japan to host the world's largest nuclear fusion experiment, after the European Commission outlined plans to proceed with the €10bn Iter project at a French site even if Japan, the US and South Korea failed to come on board.

After inconclusive talks earlier this month in Vienna, the EU appears determined to tip the balance by insisting that, unlike Japan, it has the financial and scientific capacity to build and run the reactor without the support of some of the world's leading energy producers. China and Russia are backing the EU on its proposed construction site in Cadarache, southern France, but the US and South Korea are behind Japan's bid to host the reactor in Rokkasho-Mura.