The six parties involved in an international nuclear fusion project have again failed to decide on either a French or Japanese venue for the $12 billion program.
The decision, pending since December, may now come in March.
Senior officials of the parties to the International Thermonuclear Experimental Reactor project ended a one-day meeting in Vienna on Saturday without resolving the question.
Three compromise proposals by a team of experts were presented, but Japan and the European Union insisted on their own plans to host the world's first prototype nuclear fusion reactor, according to Satoru Otake of the science and technology ministry.
The ITER project is aimed at creating the world's first sustained nuclear fusion reaction.
Japan wants to host the reactor in Rokkasho, Aomori Prefecture, while the European Union has selected the town of Cadarache in southern France as its candidate.
The officials instead agreed to hold a meeting of experts in early March to compare the two sites in terms of accessibility, earthquake dangers and other technical points, the Japanese official said.
After that meeting, a ministerial gathering may be held in March or later to make a decision, he said.