Johan Meyer, 53, appeared in a court in this town south of Johannesburg a day after his arrest on charges of being in possession of nuclear-related material and of illegally importing and exporting nuclear material.

"He was arrested on charges that he was building a nuclear weapon," said Meyer's lawyer Heinrich Badenhorst.

Press reports said that Meyer, who lives in Pretoria, was a member of an international ring involved in the smuggling of nuclear components to Asian countries, Pakistan in particular.

According to the charge sheet, Meyer is accused of acquiring material between November 2000 and November 2001 that "could have contributed to the design, development, manufacturing, deployment, maintenance and use of weapons of mass destruction."

It also states that Meyer had acquired equipment, material and plans for the design and use of gas centrifuges, used to enrich uranium, the key ingredient in nuclear bomb-making.

Meyer owns an engineering plant in the town of Vanderbijlpark, located some 80 kilometers (50 miles) south of Johannesburg.

Investigators said the probe into violations of South Africa's law on the non-proliferation of weapons of mass destruction was ongoing and did not rule out further arrests.

Spokesman Sipho Nguema for the national prosecuting authority said investigators were cooperating with international agencies but did not give details.