In his pocket they found a computer memory stick.

The 27-year-old Briton of Pakistani heritage insisted that it contained nothing but his plans for a holiday in the United States.

The police checked anyway, and found a whole lot more.

The innocent-looking device held the blueprint for what they believe was a mammoth terrorist attack to blow up at least seven airplanes over the Atlantic Ocean using liquid bombs disguised as soft drinks.

The plot would have unleashed 'death on an almost unprecedented scale', a court here was told yesterday.

Ali and Sarwar, 28, are two of eight men arrested in a series of raids in August 2006. They are accused of conspiracy to murder and preparing acts of terrorism.

Their trial in Woolwich Crown Court is expected to last eight months.

Prosecutors for the first time laid out evidence in a now-infamous scheme that paralysed airports on both sides of the Atlantic and ended the era when airline passengers could carry on board a soft drink or large tube of toothpaste.

More than 2,380 flights from London were cancelled in the week after the men's arrest.

The other defendants are Tanvir Hussain, 27; Mohammed Gulzar, 26; Ibrahim Savant, 27; Arafat Khan, 26; Waheed Zaman, 23; and Umar Islam, 29.

The men, all from the London area, have all pleaded innocent. They sat in the dock, dressed smartly and flanked by guards.

Their alleged plot targeted at least seven flights leaving from London's Heathrow Airport for New York, Washington, Chicago, Toronto, Montreal and San Francisco.

'Therefore, barring unexpected cancellation or lengthy delay, seven passenger aircraft carrying hundreds of passengers and crew depart Heathrow Airport entirely at the mercy of the suicide bombers who happen to be on board with their deadly devices,' prosecutor Peter Wright said.

The men planned to smuggle liquid explosives on board in plastic soft drink bottles.

The main ingredient in the homemade explosive was to be hydrogen peroxide; food colouring would be used to turn it the same colour as the sports drinks Lucozade and Oasis.

A sugary drink known as Tang would be mixed with the solution to add power to the explosion.

The devices would be detonated using a substance concealed in AA 1.5-volt batteries.

Pages from Ali's handwritten diary made apparent references to how the bomb materials would have been got on to the aircraft.

'Clean batteries, disguise... drink bottles... check time to fill each bottle,' one list read. 'Decide on which battery to use for D. Small is best...Select date. Five days before. All link up, prepare.'

Suicide videos were also found in a camera in Sarwar's car and on a cassette tape in the garage of his home.

The videos show the men, dressed in black and seated in front of a black flag with Arabic writing in white.

In one of them Umar Islam says: 'This is revenge for the actions of the US in Muslim lands and their accomplices such as the British and the Jews.'

He added: 'Martyrdom operations upon martyrdom operations will keep on raining on these kuffars (non-believers) until they release us and leave our lands.'

WITH INFORMATION FROM THE BBC, ASSOCIATED PRESS, REUTERS