An Al Qaeda operative who planned to blow up the New York Stock Exchange, the World Bank and landmark London hotels was sentenced to life in prison on Tuesday in the most sweeping terror case in Britain since the Sept. 11, 2001, attacks.

The judge told Dhiren Barot he must serve at least 40 years in prison.

"You have chosen to use your life to bring death and destruction to the Western world," Judge Neil Butterfield said as he passed the sentence. "You planned to slaughter hundreds, if not thousands, of wholly innocent men, women and children,"

Butterfield described the plans as determined, sophisticated and deadly.

"You were planning to bring indiscriminate carnage, bloodshed and butchery — first in Washington, Newark and New York — and then London," Butterfield said.

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Barot's plans to attack British targets had moved to their final stages as he had received approval from his superiors to strike as part of a plot to unleash a "memorable black day" of terror, the prosecutor told the court during the sentencing phase Tuesday.

"The uncontradicted evidence suggests the conspiracy was in its final stages," prosecutor Edmund Lawson said.

Though Barot had originally planned to hit high-profile targets in the United States — such as the New York Stock Exchange and the World Bank in Washington — the Muslim convert put the plans on hold after the Sept. 11, 2001, attacks. By July 2004, British intelligence officials feared an attack was imminent.

Prosecutors could not estimate exactly when Barot planned to strike.

Britain's Home Office said Barot would be temporarily transferred from his prison cell to the United States to face a four-count indictment, which includes a charge of conspiracy to use weapons of mass destruction. Officials could not confirm when he was expected to land in the U.S.

Barot began plotting, in 2000, to attack a host of financial industry targets in the United States while also planning to detonate limousines packed with explosives in the underground parking lots of famous London hotels and train stations, prosecutors said.

Lawson said Barot and seven alleged accomplices had proposals to use a radioactive "dirty bomb," ramming it into a high-profile British target.

In a dramatic exchange Monday, Lawson showed clips of a reconnaissance video taken by Barot during a 2001 visit to New York.

The shaky footage — shown on large screens in the courthouse — zoomed in on the World Trade Center's towers as an unseen man mimicked the sound of an explosion.

"It is memorable for its macabre prophecy," Lawson said, explaining that Barot was not believed to have had prior knowledge of the Sept. 11 terror attacks that killed an estimated 3,000 people.

Starting in 1995, Barot trained at terrorist camps in Pakistan, Kashmir, Malaysia and the Philippines — crisscrossing the globe to refine skills with weapons, bomb-making and chemicals, Lawson said.

He became quickly inspired to plot a "memorable black day for the enemies of Islam," Lawson said, quoting a passage from Barot's notebook.

Barot's plans were designed to kill "hundreds if not thousands of innocent people without warning," Lawson said.

He said computer files recovered by police detailed a plan to explode three limousines crammed with gas cylinders, explosives and nails after leaving them in underground London parking garages.

London hotels such as The Ritz and The Savoy, and railway stations such as London's Waterloo, Paddington and King's Cross were identified as targets, Lawson said.

The documents also contained details of a plan to attack a subway train as it traveled through a tunnel under the River Thames.

A powerful explosion would "cause pandemonium ... explosions, flooding, drowning," Barot wrote, according to a document handed to the court.

Barot made two reconnaissance trips to the United States in August 2000 and March 2001 — visiting an aunt in New Jersey on both occasions, Lawson said.

A 1-hour, 20-minute New York reconnaissance film was later discovered in London spliced into a video tape copy of "Die Hard With A Vengeance."

Lawson said the camcorder footage of buildings on New York's Broad Street and Wall Street was shot in 2001, when Barot also took two helicopter trips across Manhattan.

Prosecutors said Barot's U.S. targets included the World Bank headquarters and the International Monetary Fund, both in Washington, the Citigroup buildings in New York and the Prudential building in Newark, New Jersey.

Discovery of the plots led U.S. President George W. Bush to raise the U.S. terrorism threat level.

Under the alias Issa al-Britani, Barot was named in the report of the U.S. commission investigating the Sept. 11, 2001, attacks, as an associate of Khalid Sheikh Mohammed, the alleged Sept. 11 planner.

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 Barot's sentencing hearing.

Butterfield had ruled that publishing details of the case could prejudice trials of Barot's seven co-defendants, scheduled to take place in London next year.