One of the targets was the New York Stock Exchange

Dhiren Barot, of north London, planned to use a radioactive "dirty bomb" in one of a series of attacks in the UK, Woolwich Crown Court heard.

He intended to cause "injury, fear, terror and chaos", prosecutors said.

They also said Barot, 34, plotted to cause explosions at several US financial buildings "designed to kill as many innocent people as possible".

Prosecuting QC Edmund Lawson said plans had been found by police on a computer after Barot was arrested in August 2004.

However, he did not dispute claims from the defence that no funding had been received for the projects, nor any vehicles or bomb-making materials acquired.

The plans were for attacks on the International Monetary Fund (IMF) and World Bank buildings in Washington, the New York Stock Exchange and Citigroup buildings in New York and the Prudential buildings in Newark, New Jersey.

"These being plans...to carry out explosions at those premises with no warning, they were basically designed to kill as many innocent people as possible," said Mr Lawson.

The defendant also plotted to blow up three limousines "packed" with gas cylinders and explosives in underground car parks in the UK, the court heard.

Mr Lawson said the plot - known as the Gas Limos Project - was to form the "main cornerstone" of a series of synchronised attacks in the UK.

Other bombings being planned included a so-called "dirty bomb project".

Mr Lawson said this plot was designed to achieve "a number of further and collateral objectives such as to cause injury, fear, terror and chaos".

According to expert evidence, if the radiation (dirty bomb) project had been carried out, it would have been unlikely to cause deaths, but was designed to affect about 500 people, he said.

Barot had also faced 12 other charges: one of conspiracy to commit public nuisance, seven of making a record of information for terrorist purposes and four of possessing a record of information for terrorist purposes.

The judge ordered all these charges to lie on file following his guilty plea to conspiracy to murder.

Mr Lawson said that by pleading guilty, Barot made "no admission with regard to the involvement of any of his seven co-defendants in the conspiracy".

Seven other men are due to face trial next year.

Barot will be sentenced at a later date.