Two companies have pleaded guilty to breaching health and safety laws in connection with an explosion at a Pembrokeshire oil refinery which killed four people.

Dennis Riley, Robert Broome, Andrew Jenkins and Julie Jones died in June 2011 when an oil storage tank exploded during routine maintenance work.

Another man was left with serious injuries.

At the time of the incident the refinery was operated by Chevron Limited, but ownership changed in August 2011.

Today Valero Energy UK Ltd and B&A Contracts Ltd appeared before Haverfordwest Magistrates court.

Both companies pleaded guilty to two charges under the Health and Safety at Work Act.

The charges relate to providing a duty of care to both employees and non-employees.

At today’s hearing at Haverfordwest Magistrates’ Court, Valero Energy UK Ltd entered a guilty plea to the charges as set out by the Health & Safety Executive in relation to the incident at Pembroke Refinery in 2011.

The charges relate to Chevron’s period of ownership of Pembroke Refinery and as the incident occurred prior to Valero’s acquisition Chevron has assumed liability for the defence of the case and all third party claims, including both civil and criminal actions.

Valero is only named due to its acquisition of the refinery in 2011 after the incident. Our thoughts as always remain with those affected and their families at this time.

They are due to be sentenced on 2 November at Swansea Crown Court.