Explosion rocks Britain's only ammunition factory as firefighters rush to south Wales site run by Europe's biggest military contractor

An explosion has occurred at a military weapons factory in south Wales run by Europe's biggest military contractor.

The blast took place at the BAE Systems base in Glascoed, Monmouthshire shortly before 10.50am

MailOnline understands the explosion relates to a single shell going off at the munitions filling factory. 

Emergency services have been deployed to the site, which is spread across a large field close to the south-eastern village.

South Wales Fire and Rescue Service said in a statement: 'At 10.49am on Wednesday 17th April, an incident occurred at the premises of BAE Systems Glascoed when an explosion occurred within a building.

'All emergency services are at the scene and an Incident Control Post has been set up to deal with the incident.'

BAE says the Glascoed plant employs around 500 people. The firm is Europe's biggest military contractor with several sites across the UK.

But Glascoed is now the UK's last remaining ammunition filling facility in the country - meaning it is the last place munitions will go to have shells and other cases filled with explosive materials. 

A BAE Systems spokesperson said: 'We can confirm that there was an incident at our Glascoed facility in Wales this morning. 

'Tried and tested safety protocols were immediately enacted and emergency services attended the site. 

'All personnel are accounted for and our emergency response team continues to monitor the facility. We have launched a full investigation.'

Sources have indicated that a shell exploded on part of the site, which is spread out across a large area - understood to be a safety measure to reduce the risk of casualties in the event of an incident involving munitions.

BAE took over the plant from the British government in the 1980s after the country's Royal Ordnance Factories were privatised.

According to the firm's website, the site produces ammunition for small arms and medium-calibre weapons, as well as mortar bombs, tank ammo and artillery shells.

This is a breaking news story - more to follow.