Workers laying pipes in a southern Spanish town have stumbled upon thousands of bronze and silver-coated coins dating as far back as the third century.

Culture officials have described it as a “unique historic discovery”, which is now being looked after by Seville’s archaeology museum.

Workers came across 19 Roman amphoras – a type of storage jar – containing the coins while carrying out routine work in a park in Tomares.

They were found just under a metre underground, and the coins are stamped with the inscriptions of emperors Maximian and Constantine.

It is thought they had been newly minted and stored to pay soldiers or civil servants, with little sign of wear and tear.

Ana Navarro, head of the Archaeological Museum of Seville, told a news conference: “It is a unique collection and there are very few similar cases”.

“I could not give you an economic value, because the value they really have is historical and you can’t calculate that.”

The museum has contacted counterparts in the UK, France and Italy, and believes the find is one of the most important from the period.

Construction work has been suspended in the park while archaeologists investigate further.