Commander John Grieve, the national anti-terrorist co-ordinator, said that leads provided by underworld informers had been of "enormous benefit" in counter terrorism. The criminals have been motivated by a mixture of money, revenge, and self interest.
It was also revealed that members of the underworld are also far more willing to talk to anti-terrorist squad officers than detectives dealing in mainstream crime because they are confident they will not be arrested.
A reward of up to pounds 1m was offered in February last year following the Docklands' bomb in east London which killed two people and ended the IRA ceasefire, but until now it was unclear how useful such financial incentives are in attracting informers.
Mr Grieve told The Independent: "Information from various areas of the community, including the criminal community, has been of enormous benefit to those engaged in the counter-terrorist offensive.
"Organised crime can be seen as a web work of loose alliances and old hatreds. We can, and do, make use of this."
He went on: "We know that some criminals are motivated by money, and will pass on useful information about other criminals in return for rewards. We have encouraged officers to explore the potential with their informants in all criminal fields."
The Anti-Terrorist Branch has targeted individuals on the criminal fringes, such as shady car dealers as well as more senior villains who are likely to have contact with IRA members looking for equipment such as false identification papers, stolen vehicles and firearms.
The increased use of criminal informers is understood to be one of the new techniques deployed by Mr Grieve, who oversees anti-terrorist investigations across the country, that has helped lead to a string of successes against the IRA. Other developments have been the growth of surveillance cameras, the police anti-terrorist hotline - 0800 789 321- and closer co-operation with MI5.
Mr Grieve is unwilling to discuss individual cases and cash rewards, but it is understood that information from criminals has been fundamental in providing vital break-throughs.
Underworld figures have made it clear that they are less wary of anti- terrorist officers, who are considered less of a threat to their liberty than other police departments.
Mr Grieve said: "Criminals seem more keen to talk to the Anti-Terrorist Branch because they see us in a different light or put us in a different category, or think we have different priorities from other police officers. Perhaps this could be another example of communities defeating terrorism."
He added: "Communities defeat crime, and in saying this I include the criminal community. Criminals are vulnerable to the risk of being informed on by their own kind.
"Some of our appeals have been targeted at specific areas of the community - for example, the `dodgy' end of the motor vehicle trade, people who may have ... information about suspicious deals and activities which are of interest to the Anti-Terrorist Branch."
But Dr Clive Norris, of Hull University, who recently completed a two year study on the use of police informers, warned last night of the potential dangers of using paid "grasses".
He said: "There's a real danger if the police are becoming involved with active criminals that one of the unintentional consequences is that they may have to turn a blind eye to the criminal acts of their informers to keep them out of prison."
He said that informers provided information for a variety of reasons. "Money is the best and clearest motive. It could also be to settle old scores, in which they case may be less interested in telling the truth, or clearing the field for arms and drug dealing."Reuse content