The Health and Safety Executive (HSE) has advised swimming pool operators and organisers of youth activities to review their safety procedures.

The warning comes after the London Borough of Barnet and the Office of the Commissioner of the Police for the Metropolis were prosecuted and fined for breaches of health and safety law.

The case followed HSE’s investigation into the deaths of two teenagers who drowned in the swimming pool at the Metropolitan police Training College in Hendon, North London.

The two boys were participating in a summer play scheme that involved swimming activities at the college.

An investigation by HSE found “serious deficiencies” in the operation of the swimming pool by the Metropolitan Police Service, and poor control of the summer play scheme by the London Borough of Barnet.

Ron Wright, HSE principal inspector, said: “Health and safety isn’t about stopping fun activities and this case illustrates the tragic results when the safety of swimmers is not properly considered.

Pool operators need to make sure that there are enough lifeguards for the size of the pool and the activities taking place.”