Nuclear plants on alert after 'credible' threat

The prospect that Osama bin Laden might strike at an American nuclear facility was raised yesterday as the atomic power plant at Three Mile Island received a "credible threat".

The alert came as nuclear authorities expressed concern that Mr bin Laden's al-Qa'ida organisation was attempting to build an atomic bomb.

The airport at Harrisburg, Pennsylvania, was shut down for four hours early yesterday because of the security alert at the Three Mile Island plant nearby. Temporary flight restrictions were put into effect throughout a 20-mile radius around the airport, until federal officials were able to discredit the threat.

They said later that the plant, whose reactor had been shut down for maintenance earlier this month, remained under high alert.

As fears of germ warfare spread into the nuclear safety field, a representative of the international nuclear watchdog, the IAEA, would not rule out the possibility of "rogue state" backing for Mr bin Laden's attempts to acquire an atomic bomb.

A key prosecution witness in the New York trial stemming from the 1998 bombings of the US embassies in Tanzania and Kenya, which handed down sentences yesterday, told the court in February that Mr bin Laden had attempted to buy uranium in 1993-94.

The witness, Sudanese national Jamal Ahmad al-Fadl, said he was instructed by a senior al Qa'ida operative to meet with a contact in Khartoum who wanted to sell South African uranium for an arranged price of $1.5m (£1m).

"They took us inside house in Bait el Mal and after a few minutes they bring a big bag and they open it, and it is a cylinder, like this tall," Mr al Fadl told the court, gesturing to a height of two to three feet.

He said he remembered the cylinder was marked "South Africa" with a serial number. But he also said he was not told whether al Qa'ida actually purchased the uranium, which was to be tested in Kenya.

South Africa's nuclear weapons programme was shut down in 1991-92 and the arms destroyed under international supervision.

The New York representative for the International Atomic Energy Agency, Gustavo Zlauvinen, said yesterday there was "no evidence" to prove that Mr bin Laden's network had obtained the uranium, nor was there any evidence that subsequent attempts had succeeded.

Mr Zlauvinen said: "It's one thing to get your hands on radiological sources, you can get it through hospitals and engineering sources.

"But it is highly improbable that non-state organisations could acquire a nuclear weapon. That would require much more effort than an organisation alone could provide, because of the technical complexity. The Iraqis tried for many years, and still they didn't succeed.

Mr Zlauvinen said there was much more concern about so-called "orphan sources" of highly enriched uranium finding their way into terrorists' hands. These are the radiological sources that were produced for Soviet nuclear weapons and research reactors, and the nuclear waste from civilian reactors.

"Not even the Russians know where all those sources are," Mr Zlauvinen said. "We are helping the Russians to track down those sources."

He said that Iraq and North Korea appeared to be the most likely states who might be prepared to pass on their nuclear know-how to terrorist groups.

The UN weapons inspectors have been refused entry to Iraq since December 1998. "We cannot give any kind of assurances that Iraq has not been involved in another clandestine programme," Mr Zlauvinen said.

The IAEA has also been refused entry into North Korea, to verify that its atomic arms programme has been frozen in line with a 1994 agreement.

With regard to North Korea, the IAEA director general, Mohammed Elbaradei, said on Wednesday: We are still where we had been a year ago."