An explosion at a military hardware factory near Salisbury, Wiltshire killed a worker on Friday, British defence equipment maker Chemring Group said.
The explosion at the Chemring Countermeasures factory of the British contractor also injured another person who was taken to a hospital, the company said in a tweet.
The site was evacuated and the incident was brought under control, the company said, adding that the defence equipment maker has launched an investigation into the cause of the incident which occurred on Friday evening.
British media had earlier reported on the explosion citing the Wiltshire Police.
"We have two casualties that have been identified. One of them sadly died at the scene and the other has been taken to hospital in a critical condition," a representative of the Wiltshire Police was quoted as saying by the BBC.
Reuters could not immediately reach the police force for comment.
Chemring Countermeasures makes products to protect military ships and aircraft from attack.
Salisbury was also the place where double agent Sergei Skripal and his daughter were poisoned by the Novichok military-grade nerve agent in March.
Both eventually recovered. Britain has accused Russia of being behind the attack, which the Kremlin denies.