The top Al Qaeda operative known to be captured in Britain arrived at court amid heavy security on Monday for sentencing in a plot to bomb the New York Stock Exchange, the International Monetary Fund headquarters in Washington and other major U.S. financial targets.

Dhiren Barot, 34, started plotting in 2000 what he said would be a "memorable black day for the enemies of Islam," prosecutor Edmund Lawson said at the start of the two-day sentencing hearing.

Flanked by two court guards behind a glass wall, Barot sat expressionless as the proceedings began. Born a Hindu and raised in Britain, he pleaded guilty last month to conspiring to commit mass murder in terrorist plots on both sides of the Atlantic. He faces life in prison.

The criminal plot was to carry out massive explosions here and in the United States, Lawson said, and was meant to kill "hundreds if not thousands of innocent people without warning."

Armed guards lined the streets outside the courtroom as guards led Barot through an underground tunnel that links the court complex to the prison.

Prosecutor Edmund Lawson told a court hearing last month that Barot had planned to cram three limousines with gas cylinders and explosives and detonate them in underground London parking garages.

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Plans outlining details of the U.S. attacks, including reconnaissance videos filmed in August 2001, were found on a computer after Barot's arrest in August 2004, prosecutors said.

Discovery of his purported plot against U.S. targets that included World Bank headquarters in Washington, the Citigroup building in New York and the Prudential building in Newark, N.J. — led President Bush to raise the U.S. terrorism threat level.

He is wanted in the United States on a four-count indictment and faces a life sentence if convicted of conspiracy to use weapons of mass destruction. Under British law, domestic proceedings take precedence over an extradition.

Barot was born a Hindu in Britain, where he was raised. Friends said he had aspired to be a hotel manager. U.S. officials claim Barot converted to Islam following a visit to Pakistani-controlled Kashmir and has used the names Abu Eisa al-Hindi, Abu Musa al-Hindi and Issa al-Britani.

That last name figured in the report of the U.S. commission into the Sept. 11, 2001 attacks, which claimed Khalid Sheikh Mohammed, the alleged Sept. 11 planner, ordered al-Britani to identify bombing targets in New York and sent him to Malaysia to study Islamic extremists there.

In Britain, Barot hoped to conduct simultaneous attacks and had rough plans for "radiation or dirty-bomb projects," combining radioactive material with conventional explosives, prosecutors said.

Lawson said the dirty bomb was designed to cause "injury, fear, terror and chaos" but considered by experts unlikely to have been powerful enough to kill.

The Associated Press, The British Broadcasting Corp., and Times Newspapers Ltd. successfully challenged a court ruling that threatened to prevent news media reporting details of sentencing and details that emerged in the hearing. Judge Neil Butterfield had ruled that publishing details of the two-day sentencing hearing could prejudice trials of Barot's seven co-defendants.

The alleged co-conspirators are scheduled to face trial in Britain next year.