Tanya Oliver, 29, from Houghton, is claiming unfair dismissal, sexual discrimination and disability discrimination against her former employers, TRW Systems Ltd, at Rainton Bridge.

Miss Oliver told an employment tribunal hearing yesterday that two members of staff had made her working life in the electronics department a misery.

She said the behavior of team leader Gillian Parkin and staff member Janet Wilson had left her 'worried and stressed' about returning to work after the birth of her second son.

In September 2006, when she was five months pregnant, Miss Oliver fell down stairs at work, banging her stomach, and injuring her left leg and ankle, which led to long term problems with sciatica in her leg and back.

At the time she was wearing trainers and heel grounders, and claimed the company had not given her proper safety shoes.

But Mrs Parkin said that Miss Oliver had failed to collect her new safety footwear after repeated reminders.

Mrs Parkin said "On one occasion I told Miss Oliver she must come and try them (safety footwear) on and she said 'I'd forget my head if it was loose.'"

Following the fall, Miss Oliver said she was often picked on by Mrs Parkin and Mrs Wilson for wearing tracksuit bottoms when her pregnancy meant she could no longer wear regulation trousers, and for wearing trainers to ease her back pain.

Miss Oliver said: "I found I was being called into the office on a daily basis and also pulled to one side on a regular basis.

"I was told on several occasions my trousers had to be 100 per cent cotton. I had checked the label and was quite satisfied they met the companies requirements.

"I was asked to show them the tag inside my trousers. I refused because I had already shown Janet. At least one other member of staff who was pregnant wore tracksuit trousers and had not been criticised."

Mr James English, for TRW Systems, asked Miss Oliver: "Is it not perfectly legitimate for the company to insist you wear safety shows after a serious accident?"

Miss Oliver said she was told to bring in a pair of company issue maternity trousers from her first pregnancy so that she could be photographed in them to prove they did not fit any more, and that she was asked to show the label of her trousers to Mrs Parkin and Mrs Wilson to prove they had a high cotton content.

In her witness statement, Miss Oliver said: "I was extremely upset by this suggestion."

Mrs Parkin remembered the alleged incident differently.

She told the tribunal: "I suggested Miss Oliver use a belt to hold up her old maternity trousers and she said 'Do you want me to look like Coco the Clown?'

"I took this to be a joke and said 'That would give us all a laugh."

Workers at the factory are required to wear high content cotton trousers to reduce static electricity which can damage the circuit boards made there.

Mrs Parkin, 47, added: "I did not ask to photograph her - that is simply untrue.

"I did not ask to see the label of her trousers.

"Tanya came to the office and was upset she couldn't wear jogging bottoms. I said we would try and support her as much as possible.

"When I offered her £25 to buy maternity trousers she said 'I don't see why I should do your job for you.'

"She just totally changed. Truthfully, I think it was because I couldn't allow her to wear jogging bottoms."

Miss Oliver began her maternity leave in December 2006 but when she was due to return to work the following summer, began to feel stressed at the thought.

She said: "I grew more and more worried about going back to more of Janet and Gillian's bullying."

After writing a grievance letter to TRW Systems to which she said she had no response: she handed in her resignation.

Mrs Eva Cooper, of Howley Avenue, Sunderland said: 'Each day we would have a bet on when she (Tanya Oliver) would be called into the office.

"It's fair to say she was singled out. Tanya would tell me what she'd been taken in for."

But Mr James English for TRW Systems, said: "You wouldn't have been aware of those conversations first hand."

Mrs Cooper said: "I can't see any reason for Tanya to come out and tell me a pack of lies about what's been said."

The hearing continues today.