The Liberal Democrats are set to argue that ministers should take responsibility for plans to arm police officers with stun guns.

The party is leading a debate challenging a decision by Strathclyde Police to issue tasers to 30 officers after three days of training.

The weapons fire a 50,000-volt electrical charge and are designed to incapacitate people rather than cause serious injury.

Lib Dems maintain the move is a shift in policy, rather than an operational matter for police, and should be debated in the Scottish Parliament.

Robert Brown, the party's justice spokesman, said: "Before the weapons were issued to more officers in England, it was signed off by the Home Secretary but according to the First Minister, in Scotland this is an operational matter and he refuses to get drawn in.

"The First Minister has also given assurances that police officers who are armed with Taser guns will be given the same amount of training as firearm officers - three days is clearly nowhere near the amount of training firearms officers receive."

He added: "Safety of police officers is, of course, absolutely vital but we have always prided ourselves on having an unarmed police force which has good relations with the local community. We should not move away from this without very good reason."

It emerged last month that Strathclyde Police is to give the weapons to officers on the beat in the Cambuslang and Rutherglen areas of South Lanarkshire in a pilot scheme.