Five BAE Systems workers have been sacked for misusing the company's computer equipment.

Four of the axed employees are understood to have worked at the company's Warton site, and one was based at Samlesbury.

Their dismissal follows a two-week internal investigation; all five were suspended during the investigation. A further two employees, also suspended, are still being investigated.

On Monday workers at the firm were sent an email explaining the move. It read: "The investigation has uncovered a serious breach of policies centred around the IT Acceptable Use Policy but also involving the Respect at Work Policy.

"It is unfortunate that this position has been reached."

The company refused to give the exact nature of the breach, but did not rule out the use of pornographic material.

A spokesman said the police had not been involved, and added: "The matter will remain internal. BAE Systems has rigorous standards with respect to the use of its IT to ensure both appropriate use of its information systems, and to protect its employees from material which may be considered offensive.

"It would be inappropriate to comment further until this issue has been brought to a complete close."

The investigation is expected to last two more weeks.

But rumour on the 'shop floor' was that the matter involved pornography.

One worker who asked not to be named, said: "A lot of people have been saying it was because of porn. No one, including me, really knew about it until a memo went out on Monday.

"Everyone was a bit surprised but we've not heard anything since."

Amicus, the manufacturing, technical and skilled persons' union, has advised all five workers to appeal. It confirmed that one appeal had already been lodged with the firm, and proceedings for that are expected to be concluded within a fortnight.

In September 2002, more than 1200 workers at the firm's Samlesbury site downed tools in support of a longstanding employee, who had worked there for 25 years, who was sacked for internet misuse.

Ron Ralph, regional secretary at Amicus, said: "This did happen a couple of years ago but there has been no indication that this will happen again.

"We will represent any workers who decide to appeal and await the outcome."

A study released by security solution provider, Cyber Project, in 2003, revealed workers in Preston were joint leaders with Bolton in costing companies in lost productivity and thousands of pounds by spending an average of five hours a week at work on non-business related internet surfing.

The study revealed 62 per cent of workers in Preston admitted going online at least once during the working day for personal reasons.