Since the onset of digital mobile phones criminals have used them to strike their deals, knowing that law enforcement agencies could not listen in. Now, the technology enabling police and Customs officers to tap digital mobiles has been cracked.
A senior police source said: "It was only a matter of time before technology caught up with them and now there is no place for them to hide."
It is understood that police and Customs are already employing the new technology to target some of Britain's major criminals and international drug smugglers.
The headache for Britain's law enforcers has been caused by the development of digital mobile phones which have, until now, been beyond the range of traditional phone-tapping methods. In contrast, analogue phones were easy to monitor using a pounds 150 scanner. They gained notoriety when conversations involving members of the royal family were taped.
A Customs and Excise spokeswoman said: "We cannot talk about security matters. We do not want to give any intelligence away, particularly on sensitive subjects such as surveillance."
However, the police source said: "It's been frustrating us for years while on surveillance we can watch these guys strike their deals on their digital phones.
"It's early days, but we've already had some success listening in on mobiles. At the moment evidence we gather by this means is used for intelligence purposes only, but it may be that we will also be able to produce it as courtroom evidence."
There has been widespread concern that mobile digital phones using satellite links put many criminals outside the reach of the law. Criminals, from the small-time burglar to the international drug dealer, have shunned conventional telephone lines, fearing they were being tapped and their conversations tape-recorded.
Drug dealers are heavily reliant on the technology: Evelyn Fleckney was jailed last month for using a mobile phone from her Tunbridge Wells to transact cocaine and ecstasy deals worth million of pounds. In 1995, one of the three drug barons shot dead on a remote Essex farm track had his mobile phone cradled in his lap when found by police.
Mobiles are also popular in prisons, enabling inmates to continue their criminal activities, avoiding using land lines which are routinely monitored by the prison services.
Three years ago, amid fears that new digital systems would provide "unique possibilities for organised crime and lead to new threats to national security," Britain called for a European Union-wide telephone tapping system to permit security services to monitor international telephone calls made on satellite- based mobile digital phones.