Ashford's Stour Centre was evacuated this afternoon following a chemical spillage.

One worker was treated by paramedics at the centre in Tannery Lane and about 150 people were left waiting outside.

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Firefighters with specialist equipment were called just before 2pm after a chlorine gas leak was discovered in one room.

Earlier, incident commander Andrew McPherson said: "Approximately 150 people have been evacuated from the building. We believe an employee was mixing chemicals for use in the swimming pool. For an unknown reason the chemicals reacted badly.

"The employee was wearing the correct clothing, but complained of an irritation in his eyes. He has been checked over by paramedics. No one else has been reported as injured."

He added: "We sent in a team wearing breathing apparatus to ascertain the situation. We are currently ventilating the building using a positive ventilation fan. We're now monitoring the readings in the building and will do so until they are back down to zero. Only then will we leave."

Witnesses reported a strong smell of chlorine just before they were asked to leave the building.

Christopher Cox, 55, from Kennington, was taking part in a gym class when a member of staff asked him to leave the building.

Mr Cox, who works in retail sales, said: "There was no public announcement or alarm, just members of staff coming round. I was disappointed not to see staff in fluorescent jackets - we didn't know who was who. Quite frankly it was a bit of a poor show."

Emma Wood, chief executive of Ashford Leisure Trust, which runs the centre, said earlier: "The building was evacuated at 2pm following a report of a chlorine gas leak.

"We are currently in the hands of the emergency services and we are hoping to re-open in a couple of hours when it is safe to do so."

About 150 people - adults, children and staff - waited on the grass outside the centre.

Video: People evacuated at the leisure centre

One of the swimmers who was evacuated said: "There was a really strong chlorine smell and then we were asked to get out of the pool but no one was shouting and there were no alarms."

The centre was reopened after about two hours.

Ms Wood added: "We would like to apologise for any inconvenience caused and thank our customers on site for their co-operation and patience."