The EU agreed on Friday to press ahead with the construction of a pioneering nuclear energy project in France if Japan, the rival bidder for the facility, does not reach a deal soon.
EU research ministers in Brussels endorsed a proposal to that effect by the European Commission, which is holding talks with the five other partners in the project -- China, Japan, Russia, South Korea and the US.
The Japanese government responded by saying the Europeans' stance was "extremely regrettable" and insisted that the six-party negotiations should continue.
French Research Minister Francois D'Aubert told reporters that negotiations were being held "virtually round-the-clock" with Japan.
But he added: "Today we are in a situation that if the negotiations ... do not rapidly reach fruition, the commission has the possibility to switch tack."
For the EU's presidency, Dutch Education and Research Minister Maria van der Hoeven said the 25-nation bloc hoped for a deal "in the very near future".
"To this end the concept of a privileged partnership with Japan will be explored," she told a news conference.
The two candidate sites to host the International Thermonuclear Experimental Reactor (ITER), which would emulate the sun's nuclear fusion to generate inexhaustible supplies of electricity, are Cadarache in southern France and Rokkasho-mura in northern Japan.
Successive rounds of talks at the International Atomic Energy Agency in Vienna have failed to find a deal on what is billed as one of the most exciting ventures in international science.
Of the six partners in the talks China and Russia support the French site, while the US and South Korea back building ITER in Japan.
Van der Hoeven said the EU hoped to reach a political accord this year, in the hope of forging a definitive accord by mid-2005.
But if this proves impossible, which the EU believes is increasingly likely, the bloc would press ahead at Cadarache with China, Russia and any other nations that want to come on board.
The EU's new research commissioner, Janez Potocnik, told the ministers that a six-party deal could still be struck if Japan accepts an offer to host spin-off projects from ITER under the "privileged partnership."
Cadarache, he told the news conference, was "the most appropriate site in scientific, technical and environmental terms."
The European Commission has proposed that a "JT60" super-reactor and a research centre for analysis of fusion-related materials be built in Japan to feed into the ITER project.
Tokyo, however, insisted that the EU was jumping the gun.
"It is extremely regrettable. We hope that the EU will handle this matter appropriately and honestly," said Takahiro Hayashi, deputy director of the Office of Fusion Energy at Japan's energy ministry.
"There is no deadline for the talks. We will continue until both sides reach an agreement," he said.
ITER's budget is expected to be some 10 billion euros (US$13 billion) over the next 30 years, including 4.7 billion euros to build the main reactor. The EU plans to finance 40 percent of the total.
The project is not expected to generate electricity before 2050.