A blind man who was Tasered by police who mistook his white stick for a samurai sword launched a claim for compensation on Thursday.

Colin Farmer, 63, was shot in the back with a 50,000-volt Taser stun gun on October 12 last year in Chorley, Lancashire, after police received reports of a man walking through the town with a sword.

One policeman thought he had tracked down the offender and asked Farmer to stop. When he failed to do so, he was stunned with the taser gun.

Farmer, who has suffered two strokes, was walking to a pub when the police officer struck, and said afterwards that the attack left him "shaking like a leaf" and scared to go outside.

Once police realised their mistake, Farmer was rushed to hospital, where he was released after a check-up.

A different man was later arrested on suspicion of possessing an offensive weapon in the town, while police apologised for the mistake and Farmer's "traumatic experience".

On Thursday Farmer's lawyer wrote to Lancashire Constabulary claiming damages for assault, false imprisonment and a breach of his human rights.

He is also seeking a declaration from the High Court that the user of the Taser was incompatible with Britain's obligations under the Human Rights Act.

The case has also been referred to the Independent Police Complaints Commission.