The Metropolitan police is to boycott the home secretary's plan to arm 10,000 frontline officers with Taser stun guns because of their potential to cause fear and damage public confidence.

The Metropolitan Police Authority said yesterday it had no intention of immediately taking up Jacqui Smith's offer to sanction an increase in the availability of Tasers. "We recognise the potential to cause fear and damage public confidence if the use of Tasers is extended to non-specialist trained police officers and is perceived by the public to be indiscriminate," the MPA said. "There is no doubt that in some circumstances Tasers are a very effective alternative to firearms or asps [metal batons] but their use must be tightly controlled and we have seen no case made out to extend their availability."

The home secretary defended her decision to make the weapons available to officers, saying she wanted to give them the tools they need to confront dangerous people. "I'm proud that we have one of the few police services ... that does not regularly carry firearms. But every day the police put themselves in danger to protect us, the public," she said.

The decision follows a 12-month trial in the use of the 50,000-volt weapons involving specially trained officers in 10 forces. The stun guns were deployed on 600 occasions during the trial but were discharged only 93 times as officers found their threatened use was sufficient to resolve difficult situations.

The Independent Police Complaints Commission said 35 complaints had been made against the use of Tasers since they were introduced in 2004 for use by firearms officers in the UK. The IPCC added that it backed the extension of the use of Tasers.