LONDON (AP) _ One of the top al-Qaida operatives known to have been captured in Britain appeared in court amid heavy security Monday for sentencing in a plot to bomb the New York Stock Exchange, the International Monetary Fund headquarters in Washington and to use a dirty bomb in London.

Dhiren Barot, 34, started plotting six years ago for a ``memorable black day for the enemies of Islam,'' prosecutor Edmund Lawson said at the hearing, which was punctuated by a dramatic moment when prosecutors showed a March 2001 video shot while Barot was in New York. The camera zooms into the World Trade Center and a man is then heard mimicking the sound of an explosion.

``This, we have to bear in mind, was five months before 9/11,'' Lawson said.

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

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

Barot planned to cram three limousines with gas cylinders and explosives and detonate them in underground London parking garages, Lawson said. He also identified London hotels such as The Ritz and The Savoy, and railway stations such as London's Waterloo, Paddington and King's Cross as targets. Other attacks in Britain included using a dirty bomb, although experts question whether it would have been lethal.

In computer files recovered by police, Lawson said Barot planned to bomb a subway train as it traveled through a tunnel under the River Thames.

``If a powerful explosion were to rip through here and actually rupture the river itself, this would cause pandemonium ... explosions, flooding, drowning,'' Barot wrote in the computer documents found, according to Lawson.

Barot was born a Hindu in India but was brought to Britain as a toddler. He converted to Islam when he was about 20, Lawson said.

After leaving his job as an airline ticket clerk in Britain, he went to Pakistan and attended a terrorist training camp in the Pakistan-controlled area of Kashmir for at least four months, Lawson said.

Investigators confiscated Barot's notes that showed he gained extensive training in the use of weapons, chemicals and bomb design. In 1998, he traveled to Malaysia and the Philippines in 1999, where he attended the Jamaah al-Islamiya terror training camp, Lawson said.

In August 2000 and March 2001, Barot went on two reconnaissance trips to the United States, Lawson said.

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 the World Bank headquarters in Washington, Citigroup headquarters in New York and the Prudential building in Newark, N.J., led President Bush to raise the U.S. terrorism threat level.

Barot and an alleged accomplice arrived in New York in 2000 and told immigration officers they were tourists, giving an address of a hotel in the city, according to Lawson, who said the pair stayed with Barot's aunt in New Jersey before driving a rental car to Washington.

On a second trip with another alleged conspirator in March 2001, Barot told his aunt he was planning to visit California and meet a group of girls. Instead, Barot went to Washington and also took a helicopter trip across Manhattan.

It was this 2001 trip to Manhattan when prosecutors said the video of the World Trade Center was shot.

``It is memorable for its macabre prophecy,'' said Lawson, who said he didn't think Barot had prior knowledge of the Sept. 11 attacks.

Four computer files found by investigators showed blueprints of buildings, including a detailed structural plan of Washington's World Bank building. Each file included photographs and suggested attack methods.

In a book published under the alias, Eisa al-Hindi, Barot called for attacks against the West and said ``the most favorable target would be the national economy of the Western bloc.'' He also claimed that he trained fighters in Afghanistan, although details of that trip were unclear.

Prosecutors said British intelligence agents put Barot under surveillance in June 2004, but in July, their target was ``temporarily lost from sight and there was concern that an attack in this country may be imminent,'' Lawson said.

British authorities captured him in a London barber shop on Aug. 3, 2004.

During raids at the homes of alleged accomplices, police recovered encrypted DVDs hidden in a toybox. Officers also seized videotapes, including a copy of ``Die Hard with a Vengeance,'' which had more than an hour's worth of footage of New York hidden at the end of the film.

The shaky camcorder film, which Lawson said was shot in 2001, showed buildings on Broad Street and Wall Street. It also contained details of entrances and security barriers at the New York Stock Exchange and the Citigroup headquarters.

Lawson played the footage in court, freezing the video that showed a man identified as Barot walking into view on Wall Street.

Barot 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. He is also wanted in Yemen for the 1988 kidnappings of Westerners.

Friends said he had aspired to be a hotel manager. He is also known 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.

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

The alleged coconspirators are scheduled to face trial in Britain next year.