UK wiretap mistakes "unacceptably high" - watchdog

LONDON, Feb 20 (Reuters) Mistakes by British law enforcement agencies in intercepting phone calls reached an ''unacceptably high'' level as pressure intensified around the time of the 2005 London bombings, a watchdog said yesterday.

''The number of errors is unacceptably high,'' said Swinton Thomas, a former judge who recently completed his term as a government-appointed watchdog into how wiretaps are carried out.

''It should, however, be stressed that ... there have been periods of time in the course of the last 18 months when the relevant intelligence and law enforcement agencies have been working under extreme pressure, with some employees working round the clock.'' He added these pressures made it more likely that mistakes would occur and more understandable when they did.

Errors, such as confusing the number of the telephone to be tapped, had risen to 66 between January 2005 and March 2006, up from 45 in 2004, the annual report said.

Thomas said any information obtained in this way had been destroyed.

Anti-terrorist police say they have thwarted at least five major plots since July 2005 when four British Islamists blew themselves up on London's transport network, killing 52 commuters and wounding hundreds.

British security services have to obtain a warrant from a minister before they can intercept the phone or e-mail of someone believed to be involved in terrorism or serious crime.

The report showed 2,243 warrants to intercept communications had been issued between January 2005 and March 2006.

Thomas spoke out against a growing chorus of politicians who want intercept evidence used in court.

In most Western countries, police intercepts of suspects' phone conversations may be used as evidence in court, but it is not allowed in Britain.

Finance minister Gordon Brown, London police chief Ian Blair, a parliamentary committee and civil rights groups have been among those calling in recent months for wiretap evidence to be used in court.

Thomas said events surrounding the London bombings had only strengthened his view that intercepts should not be used in court.

If terrorists and criminals knew that interception would be used in evidence against them, ''they will do everything possible to stop providing the material which is so very valuable as intelligence,'' Thomas said.

The cost of transcribing intercept evidence would be high and would add greatly to the workload of law enforcement agencies, he said.

Thomas also criticised a guarantee given to members of parliament since the 1960s that their communications would not be intercepted by law enforcement agencies.

The policy was wrong because it meant members of parliament were above the law, he said.

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