Paris

Ministers from the partners in ITER, a US$5-billion international fusion experiment, have postponed a meeting scheduled for this month to select a site for the project.

The delay has been caused by deadlock over the choice between France or Japan as host for the project, which would seek to prove the principle of creating fusion energy by heating plasma constrained by a magnetic field.

Negotiations over ITER's site have been stalled since a ministerial meeting in Washington in December, when the United States and Korea backed the Japanese site at Rokkasho, and China and Russia supported the European Union's site at Cadarache in France. Negotiators asked France and Japan to answer questions on the technical merits of each site, and to consider making the experimental reactor into part of a broader, international fusion-research package.

The ministers agreed to reconvene in February but, with no agreement in sight, another failed meeting “would have given the impression that the whole ITER process was falling apart”, according to an official close to the negotiations. Now ITER's backers hope a delay will help draw the political sting from the negotiations, which have been overshadowed by the perception that the United States is supporting Japan out of a desire to punish France for its stance over last year's invasion of Iraq.

The broader research programme would look, for example, at how the reactor walls of a future fusion power plant stand up to radiation damage, and at superconducting magnets. Such a programme would cost about $800 million, and would be seen as a way of compensating the country that doesn't get to house the main experiment.

In the absence of a ministerial meeting, government officials connected to ITER will meet in Vienna on 21 February to try to break the deadlock.

Meanwhile, the European Union and Japan are engaged in talks in a bid to find a way forward. One European official says that the European Union is offering South Korea and Japan support for projects ranging from genomics to neutron science, if they will support the French bid to host ITER.