The taser stun gun is being trailed by North Wales Police

A man being arrested was hit with the gun - which uses darts and wires to deliver a disabling 50,000-volt electric shock - three times in an incident in Rhyl on Wednesday night.

The force said officers had reason to believe the man was armed with a carving knife and he appeared at the door of a property making threats and threw a glass object at police.

After his arrest, the man was examined by a police surgeon for minor injuries but was otherwise fit and well and is being detained at Rhyl police station.

Bill Brereton, North Wales Police's deputy chief constable, said officers were called to a domestic incident in which a woman had apparently been stabbed.

He said one man was arrested without incident but the second man barricaded himself into the home.

Officers must shout a warning before using the weapon.

"He was clearly threatening violence and was being abusive," said Mr Brereton.

"Three tasers were fired at him and that put him down."

He said an investigation into the deployment of three of the weapons at the same would be carried out but he defended the decision to use them.

"It does appear to have been a highly effetive use of force. The man received no inuries apart from very small puncture wounds where the barbs has stuck in.

"This appears to me to be a violent man who could otherwise have been shot with a lead bullet."

The taser, which transmits an electrical impulse into the body, is being trialled as a less lethal option for disabling a suspect than conventional firearms.

Dog was targeted

North Wales Police began trialling the Taser gun, which is intended to provide a non-lethal alternative to firearms, in April this year.

The force joins the Metropolitan Police and forces in Thames Valley, Northamptonshire and Lincolnshire in testing the weapon.

It has used the weapon before, against a dog in Tanyfron, near Wrexham, which had bitten two people and was about to attack on officer. The dog was not claimed and was later destroyed.

The gun fires two darts connected to electric cable into the target before a 50,000-volt charge knocks the suspect out.

Its introduction follows growing pressure for a "less lethal" weapon to reduce the number of people shot dead by armed police.

Concerns about safety

But Amnesty International say Tasers inflict "intolerable pain" and are easily abused.

The civil rights groups also have concerns about the safety of the weapons.

"Clearly we are unable to say what the effects are of being hit simultaneously with three Taser weapons," said Robert Parker, Amnesty International UK's arms campaigner.

"They should only be used where the only alternatives are firearms - and with the same safeguards that apply to the use of firearms, including the use of specially trained officers.

"Amnesty International has been asking the UK Government for details of any testing carried out on Tasers," he added.

Firearms officers have been ordered to shout: "Taser! Taser! Taser!" before firing at suspects believed to be armed or dangerous.

The Rhyl incident has been referred to the Police Complaints Authority as a matter of course.