Explosives were discovered attached to the underneath of a lorry in Sussex on Thursday.

Two plastic cases containing guns, grenades and ammunition were found underneath the HGV, held on by magnets, at Rosier Business Park in Sussex.

Armed police and military bomb disposal teams swooped on the area in dramatic scenes.

The area was surrounded by officers and a 100metre exclusion zone was set up as buildings were hurriedly evacuated.

Police said armed officers along with officers from the National Crime Agency cordoned off part of Rosier Business Park in Billingshurst this afternoon

The National Crime Agency (NCA) confirmed they were investigating the driver for importing explosives.

The driver, a man in his 40s, was arrested at the scene.

The huge bust comes as police have been put on high alert around Windsor, for the wedding of Prince Harry to Meghan Markle.

Anti-terror barriers have been erected around the town centre and on the route leading to the castle.

Britain is currently on high alert with the security services warning the threat level for international terrorism is 'severe'. According to MI5, this means an attack is 'highly likely'.

NCA Branch Commander David Norris said: 'This was a significant seizure of weaponry which, in criminal hands, could have caused untold damage.

'Criminal gangs use these types of weapons to bring fear and violence to our streets. 'We're committed to doing all we can to stop them, and in seizing these deadly items we have made the public safer.

'I'd like to pay tribute to our colleagues from Sussex Police and the army who played such a crucial role in today's operation.

'I'd also like to thank businesses in the vicinity of the Rosier Business Park for their patience in the face of considerable disruption.

'NCA officers remain on the scene and we expect them to be there much of the night. Our investigation into the source and end destination for these weapons continues.'

Armed officers from Sussex police were also involved.

National Crime Agency officers cordoned off part of Rosier Business Park in Billingshurst on Thursday

A Sussex police spokesman said: 'Armed officers from Sussex police assisted NCA officers in the arrest of a driver of a lorry at Rosier Business Park.

'The arrest was carried out safely and without untoward incident.

A man from the Brighton area was arrested on Thursday afternoon after a lorry carrying hand grenades was intercepted

'The business park itself was evacuated as a precaution but there have been no evacuations of local areas and local people remain safe.

'There is no threat to local people.'

In total NCA officers seized three hand grenades and five handguns.

The driver, a man in his 40s from Brighton, was arrested at the scene and is now being questioned by NCA investigators at an undisclosed location.