WAR ON TERROR: AL-QAEDA 'DIRTY BOMB' PLOT FOILED BY THE FBI.

Byline: KEITH McLEOD 

AMERICAN agents have foiled an al-Qaeda plot to detonate a radioactive "dirty bomb" in Washington DC, it was revealed yesterday.

The device could have killed thousands and left much of the Washington area with radioactive contamination.

The man suspected of planning to build and plant the bomb is an American who joined al-Qaeda after converting to Islam.

Abdullah Al Mujahir was arrested in Chicago after returning from Pakistan, where he had been hatching the plot with others in Osama bin Laden's terror network.

US Attorney General John Ashcroft said: "We have captured a known terrorist who was planning to build and explode a radiological dispersion device in the United States.

"He trained with the enemy, including studying how to wire explosive devices and researching radiological dispersion devices."

President George W Bush said: "We have a man detained who is a threat to the country. He is now off the streets, where he should be."

Al Mujahir was one of two men working on the bomb. The second suspect has been arrested in Pakistan.

FBI director Robert Mueller said the plot was in the initial planning stage but there had been "substantial discussions". No date had been set for its detonation.

Officials were tipped off about Al Mujahir by Abu Zubaydah, the al-Qaeda commander who was captured this year.

His information was backed by "multiple, independent, corroborating sources".

Al Mujahir, a former Chicago street fighter, was arrested at Chicago's O'Hare airport last month while returning from Pakistan and brief stays in Zurich and Cairo.

FBI agents followed him on the final leg of the flight from Switzerland.

Since his arrest, Al Mujahir has been in custody in New York. Yesterday, he was taken to a US Navy prison in South Carolina, where he is being treated as an "enemy combatant" who poses a serious and continuing threat to US citizens.

Al Mujahir changed his name from Jose Padilla when he converted to Islam while in prison in the early 1990s.

After his release, he travelled to Afghanistan and Pakistan for training in al-Qaeda camps.

The terror network thought he was valuable because he carried a US passport and could travel freely in the States.

Last night, Ashcroft, speaking in Moscow where he is meeting Russian officials, said Al Mujahir's arrest was a "significant step forward" in the war against terror.

He added: "To our enemies, I say we will continue to be vigilant against all threats, whether they come from overseas or at home in America.

"EASY WAY TO TRIGGER PANIC

A DIRTY bomb is the ideal weapon for terrorists, according to experts.

It is relatively easy to build and uses a conventional explosive, such as dynamite, to shower an area with radioactive material.

Such an attack would not cause extensive damage but would trigger widespread panic.

To build a nuclear bomb, highly enriched uranium or plutonium are needed. Both substances are kept under tight security.

But a dirty bomb only needs a radioactive substance such as cobalt-60 or strontium-90 which are used in hospitals, or for research.

Last month, the US Nuclear Regulatory Commission said it received an average of 300 reports a year of small amounts of radio-active materials going missing.