Three men were secretly filmed handling the biggest cache of explosives ever found in Hong Kong, with the destructive potential to blow up any building in the SAR, a court heard yesterday. The three - alleged accomplices of a man referred to as 'Person A' - pleaded not guilty in the Court of First Instance to possessing almost 820kg of explosives with intent to endanger life or property. They allegedly hid the cache in an isolated ivy-covered shack near the border. 'If detonated, that quantity would have caused an enormous explosion, big enough to virtually destroy any building in Hong Kong and kill or injure people within a radius of 300 metres,' government prosecutor Michael Arthur said. 'All that was required was a box of matches.' Chan Sum-yau, 46, Wong Fung-kei, 43, and Lau Cheuk-fan, 32, each played a role in transporting the explosives - a mixture of ammonium nitrate, fuel oil and TNT - 495 metres of safety fuse and 1,997 detonators using vans and cars, including a silver Mercedes-Benz, the court heard. Police worked day and night from January 8 to January 17 last year secretly videotaping the men moving the explosives from a high-security compound in Tai Wo Village near Sheung Shui to a building in Ma Tso Lung on the border, Mr Arthur alleged. Chan and Wong were arrested at the Ma Tso Lung house in a police raid on January 17 while Lau was arrested at his Sai Kung home. Traces of ammonium nitrate were allegedly found on a pair of Lau's slippers and similar traces were said to have been found on the hands and property of Chan and Wong. The fingerprints of Person A were also found at the Ma Tso Lung house, the court heard. Prosecutors allege the chemicals were particles spilled from 326 bags of explosives seized from the house, allegedly bought by Chan under a false name six months before. 'This is no ordinary building, as you will find out,' Mr Arthur told jurors. 'It has the outward appearance of an old rusting tin shed, substantially overgrown with ivy - the sort of place you probably wouldn't notice as you drove by.' However, a completely new building was built inside the dilapidated shell, with two rooms and a cockloft. 'It was in the cockloft in this most secret of hiding places owned by [Chan] that boxes of explosives, detonators and safety fuse were taken by [Wong] and [Lau] and hidden in a most cunning way,' Mr Arthur said. He said the explosives were moved to Ma Tso Lung from the compound in Tai Wo Village, which had been bought by Wong in the name of his 78-year-old mother, Li Kiu. The court will see videotaped evidence from police in which the three defendants, Person A and Lau's brother, Lau Ting-fan, allegedly transport the explosives. The case continues before Mr Justice Peter Nguyen.