A judge at Mold Crown Court said that although injuries were minor the company had "flagrantly breached" health and safety laws at a plant it used to operate at Amlwch on Anglesey.

BBC Wales's Roger Pinney reports from Mold Crown Court

The court heard that half a ton of toxic bromine was released in a bright orange cloud which hung over the town.

If the wind had been blowing in a different direction, the lives of employees and people living nearby could have been put at risk.

It was stressed that no-one outside the bromine manufacturing site - since taken over by Great Lakes Chemicals Corporation - was actually put at risk and that there was no environmental damage.

The court heard the discharge in July 1997 was probably due to a valve being fully or partly closed, causing a build-up which eventually caused a cloud of bromine to be released above the works.

A judge called it a "flagrant breach" of health and safety laws

Bromine can cause burning to the skin and eye irritation. Prolonged exposure in extreme circumstances could be fatal.

In Anglesey the employees and attending firemen suffered superficial burn injuries, but all had made a full recovery.

The company had been convicted of similar discharges of another chemical from its premises in Ellesmere Port which resulted in a conviction in June 1996.

"This was a flagrant breach of the Acts of Parliament designed to protect both employees and members of the public, said Judge John Rogers.

Prosecutor Andrew Long said that the accident was forseeable and that a hazard report which had drawn attention to the problem had not been attended to.

Workers and firefighters suffered superficial burns

Anxious local people called the authorities but at that stage the company had not raised the alarm.

Defending, David Manley stressed that company officials had been more concerned about dealing with what was happening in front of their eyes at the time of the discharge.

They had co-operated fully with the authorities, he said, and had conducted their own extensive investigation.

It was the result of that investigation that had produced the basis of the prosecution against them.

Work had since been carried out which ensured that such a thing could never happen again, he said.

The company admitted four charges of failing to ensure the health and safety of its employees, those visiting the site - including the firefighters - failing to use the best available techniques to avoid the release and failing to notify the authorities immediately.

Graham Leathes of Asscoiated Octel outside Mold Crown Court

After the case, Health and Safety Executive Inspector Ron De Cort said: "The company should have taken steps to ensure that such a thing could not happen.

"It was only a matter of chance that no one was seriously hurt."

Richard Shone, the company's director of safety and the environment, said: "The cloud at no time posed any threat to the local community and the company is gratified that this has been confirmed by the authorities."

"The company apologise unreservedly to the local community for the concern and inconvenience caused by the incident."

Judge Rogers imposed a total fine of £180,000 and ordered the company to pay agreed costs of £80,000.