Belgium and France have the technology to convert nuclear weapons-grade material into MOX fuel that can be used in civilian nuclear power plants, while the United States does not.

Prime Minister Guy Verhofstadt, who heads a three-party coalition of his centre-right Liberals, the Socialists and environmentalist Greens, supports the request but the Greens wrote to him last month urging him to reject the request.

The row has been conducted in an exchange of letters thus far but a government spokesman said the cabinet would discuss the issue last week. He declined further comment.

A U.S. embassy spokesman said Washington planned to licence the technology to build two similar plants in the United States, but it first wanted to ship a small amount of plutonium to Belgium or France to simulate the procedure in a test facility.

"The only thing that would come, would be a test amount to build the test assemblies, process them, send them back to the U.S., run them through a plant and say here's what we get, here's how much it costs, here's what the process would be if we build this plant and here's what we get as a result," Joseph MacManus told Reuters. "That's the whole package right there."

DISARMAMENT ROLE FOR BELGIUM

MOX combines plutonium and uranium oxide recycled from spent nuclear fuel.

In a letter obtained by Reuters, Verhofstadt responded to the Greens by saying Belgium should play a part in disarmament.

"Belgium's agreement in principle would constitute an important signal that our country is prepared to contribute to the international nuclear disarmament programme, reducing the current non-proliferation risk and the problems involving the physical protection of nuclear material," he wrote.

Verhofstadt said Washington was considering recycling the plutonium at Belgonucleaire, a Belgian subsidiary of French state nuclear reprocessing firm Cogema, or at a plant in France.

It would take the United States several years to build its own MOX plant and Belgian approval of the U.S. request would speed up the destruction of weapons-grade plutonium by four years, Verhofstadt said.