A mix-up of chemicals which led to a swimming pool releasing toxic gases has landed the fitness firm which runs it a fine.

Fitness First in Thomas More Square, Wapping had to be evacuated by fire fighters after sulphur dioxide – a toxic gas which can lead to difficulties in breathing and chest pains - was released into the air.

Environmental health officers found the accident had occurred because the wrong chemical had been added to the water – something they had warned could happen in a previous inspection.

Officers had carried out an earlier inspection before the accident on September 10 which found that chemicals were being stored inadequately.

Fitness First pleaded guilty of breeches to health and safety and was fined �2,500 and ordered to pay costs of �2,000 at Thames Magistrates’ Court on August 19.

A Tower Hamlets spokesperson said: “The council’s environmental health Officers carried out an investigation and found that the company had failed to act on the findings of an earlier inspection that may have well prevented this chemical incident.

“Businesses have a legal duty to adequately manage all aspects of their business to ensure the health and safety of their employees, customers and contractors who may visit their premises.”

Fitness First insisted health and safety is a “high priority” at its clubs.

A spokeswoman said: “Since the incident, we have reviewed and improved all measures in place to ensure we are maintaining the highest standards of health and safety across all clubs.”