BOMB disposal experts carried out a controlled explosion at the Sellafield nuclear reprocessing plant after concerns were raised over chemicals stored in a laboratory.

A small number of canisters of solvents, which had been on the West Cumbrian site since 1992, were identified as potentially hazardous during a routine audit.

Sellafield Ltd said it was "not a radiological event".

However, there were concerns the chemicals, which are no longer used at the plant, could become hazardous if exposed to oxygen.

In a statement issued as the incident unfolded on Saturday, Sellafield Ltd said: "These chemicals are used extensively in many industries and are well understood.

"Because this is happening on the Sellafield site we exercise extreme caution and leave nothing to chance."

The statement said a team from the army's Explosives Ordinance Disposal Team dealt with the chemicals by digging a trench, burying them using sandbags and carrying out a controlled detonation.

It is understood the chemical, once crystalized, had the potential to become unstable and pose a significant fire hazard if exposed to air.

The anti-nuclear campaign group CORE said it was told by Sellafield Ltd that the unnamed laboratory was located in the site’s Separation Area.

The company denied that any workers had been evacuated from the site, although a cordon had been set up some 100 metres around the laboratory and workers had been evacuated from buildings within that area.