RESENDE, Oct 19: Three UN nuclear experts on Tuesday began a day-long inspection at a Brazilian uranium-enrichment plant, but Brazilian authorities insisted on giving the inspectors limited access to the centrifuges to protect trade secrets.

The International Atomic Energy Agency (IAEA) inspectors agreed to Brazil's restrictions Monday and arrived at the Resende plant at 1400 GMT Tuesday. During their visit, they were to determine whether the agreed restrictions will impede their work.

"We agreed on the details of the visit, which will allow them to say whether our plant conforms with the blueprints and design information that we sent IAEA before construction," Odair Dias Goncalves, the president of the National Nuclear Energy Commission (CNEN), said Monday.

On Tuesday, reporters were kept away from the power plant, which is located in Rio state in southeast Brazil.

Science and Technology Ministry spokesman Gustavo Souza Junior said officials from CNEN and the Bilateral Brazilian-Argentine Control Commission (ABAC) were participating in the day-long inspection.

The IAEA experts are from the United States, France and South Africa. The inspectors will not be allowed to see the centrifuges' frame, but they will have access to the tubes, valves and connections.

Brazil, which has one of the world's largest uranium reserves, denied IAEA inspectors access to the facility in February and March. Brazilian officials say they want to protect its technological secrets. But both sides changed stances on Monday, Goncalves said.

"Before, IAEA access to nuclear plants had to be complete," he said. "Today, the IAEA accepts the fact that it is not necessary to have unlimited access to facilities to obtain viable guarantees."

IAEA inspectors want to ensure that Brazil is respecting the nuclear Non-Proliferation Treaty (NPT). IAEA director general Mohamed ElBaradei has said Brazil should not be an exception to the organization's norms.

Uranium enrichment makes fuel for civilian reactors but can also be used to make atomic bombs. The IAEA is mandated under the NPT to make sure member states do not divert nuclear material for military purposes.

The US government has said that it was confident Brazil was not developing nuclear weapons.-AFP