The authority overseeing Britain’s largest police force warned that a government decision to allow Taser stun guns to be used by non-specialist firearms officers threatened to cause “fear” among the public.

Jacqui Smith’s announcement that 10,000 of the weapons are to be supplied to 43 forces in England and Wales suffered an immediate blow when the Metropolitan Police Authority said it had no intention sanctioning their wider deployment in London.

The move by the Authority, which oversees the Metropolitan Police, cames as Amnesty International warned of the danger that officers would start using Tasers on a routine basis.

After trials in which front line officers in ten forces have used the Taser gun, Ms Smith said that £8m is to be spent on supplying 10,000 weapons to all forces. At present, only specialist firearms officers carry the guns - but this will now be extended to an estimated 30,000 front line officers who have been trained to use the weapon.

Tasers, which are manufactured in the United States, deliver powerful electric shocks up to 10 metres away, leaving targets incapacitated and easier to arrest.

Officers shoot two barbed darts trailing wires from a special gun, which then deliver the electric shot of about 50,000 volts.

Within hours of Ms Smith making the announcement, the Metropolitan Police Authority warned that allowing Tasers to be used by non-specialist firearms officers had the potential to cause “fear” and “damage public confidence” in the police.

The Authority said it had no intention of sanctioning an increase in the availability of Tasers in London.

A spokesman for the Metropolitan Police Authority said it would not take up the offer of funding immediately because of the potential of Tasers to cause “fear” and “damage public confidence” in the police.

He said: “The MPA has no intention of immediately sanctioning any increase in the availability of Tasers to officers in the Met.

“The current arrangements in the Met are that only trained and supervised specialist officers may deploy Tasers, and were introduced after an extensive consultation and communication programme with London’s communities.”

The Home Secretary said the police needed tools to protect themselves and the public, but critics warned of the danger that officers would start using Tasers on a routine basis.

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