WASHINGTON, May 29: The United States hailed on Friday Malaysia's arrest of a black market nuclear agent, saying it could be a breakthrough in global efforts to dismantle global illicit nuclear network.

"We're delighted by the arrest," US State Department spokesman Richard Boucher told reporters. "This is decisive action that's been taken by the government of Malaysia."

"We think his arrest is a major step and it will serve as a catalyst to international efforts to shut down (Dr Abdul Qadeer) Khan's network."

Sri Lankan businessman B.S.A. Tahir, described by President George W. Bush this year as Khan's "chief financial officer and money launderer," was arrested on Friday in Kuala Lumpur as a threat to national security, government officials said.

The arrest of Tahir came as a surprise after government officials repeatedly said he had apparently not violated any regulations and was "a free man."

Mr Boucher said Tahir "is one of the most important figures" in Dr Khan's network," having served as chief financial officer and "essentially ran network operations.

He said the United States encouraged all states with individuals or companies tied to the network to take similar action.

"So this is an action taken by the government of Malaysia. We think it's a good thing," he said.

Malaysia is a signatory to the Nuclear Non-proliferation Treaty (NPT), which governs the movement of nuclear weapons materials, such as uranium, but it has not signed an additional protocol covering nuclear-related parts.

Malaysia said that it did not see the need to sign the protocol "at present".-AFP