A 43-year-old man was arrested on Wednesday afternoon on his smallholding outside Mbombela, after a large stash of weapons and ammunition were discovered, Mpumalanga police said.
Among the weapons there is believed to be at least two automatic assault weapons used by the SA National Defence Force - an R1 (which was used until the early 1990s) and an R4.
The police responded to a tip-off about the stash on the smallholding on the Uitkyk Road, said provincial spokesperson Brigadier Leonard Hlathi.
A reaction team made up of police, explosive experts and members of the rapid response unit raided the small holding around 14:30.
They found a blue shipping container in which more than 120 rifles, among them hunting rifles, shot guns, old .303 guns, as well as the defence force weapons, were discovered.
Many pistols and revolvers were also discovered. Most of the weapons were packed in brown coloured wooden and metal crates, which are usually used by the defence force.
Hlathi said they also seized thousands of rounds of different types of ammunition.
One of the charges being investigated against the man is the storing of the weapons in a shipping container.
"This is against regulations of the Firearms Act, because the weapons should be stored in an approved safe. We are also investigating a case of illegal possession of weapons and ammunition.
"We have arrested the suspect and he will appear in court tomorrow," said Hlathi.
SANDF spokesperson Brigadier General Mafi Mgobozi, was not immediately available for comment. The article will be updated once comment is received.