Insurers' bid to recoup their multi-million pound losses from the Buncefield oil depot explosion took a step forward this week.

Norwich Union (NU) confirmed that its lawyers had written to the owners of the fuel depot which exploded in December.

Dominic Clayden, NU director of technical claims, said it was time for the owners, Chevron-Texaco and Total Oil "to make a decision on liability".

Clayden said that while there had been discussions about a class action with other insurers to recover their losses, NU would not wish to go "at the pace of the slowest".

He would not confirm the level of NU losses from the explosion.

Meanwhile, AXA also suggested it would not be pursuing a class action.

David Williams, claims director at AXA, said the insurer had taken legal advice on pursuing its own claim.

However, he said the insurer was considering "sharing information".

AXA is understood to have £46m worth of claims from the explosion.

This week an investigation into the cause of the fire was delayed due to the scale of the damage.