A crisp factory worker with a chronic stammer needed psychiatric treatment after being forced to speak in public by his bosses at Walkers, an industrial tribunal heard yesterday.

Kevin Alderson, 40, of Easaington Colliery, County Durham, told how he was bullied and humiliated so much that he quit his job of 23 years.

Married father-of-two Mr Alderson had worked for the company since 1977, at its factory in Peterlee, County Durham.

He described how line manager Mary King frequently reduced him to tears by her bullying.

The problems started when packaging technician Mr Alderson was asked to join in a role-playing exercise and verbal presentation, in July 1999.

He told his line manager he did not want to take part because he was embarrassed about his stammer, but she bullied him into taking part.

In a statement read to the Newcastle tribunal, Mr Alderson said: "I was totally embarrassed and other colleagues were smirking at me, making my embarrassment even worse."

He described two incidents when he was belittled and had his work criticised for no reason.

Mr Alderson said: "It was verbal anguish I have never experienced before. I was driven to the point that every drop of self-esteem and confidence I had was taken from me."

Mr Alderson complained about his treatment, but after an investigation bosses told him they would take no action.

He said he had no choice but to walk out of his £16,000-a-year job in May last year.

The tribunal continues.