Workers laying pipes in a southern Spanish park have unearthed a 600-kilogram (1,300-pound) trove of Roman coins in what culture officials say is a unique historic discovery.

The Seville Archaeological Museum says the construction workers came across 19 amphoras containing thousands of unused bronze and silver-coated coins dating from the end of the 4th century.

The coins are believed to have been recently minted at the time and had probably been stored to pay soldiers or civil servants.

Museum director Ana Navarra said the discovery this week in the park in the southern town of Tomares outside Seville is unique for Spain and of incalculable value.

The regional cultural department said Friday construction work in the park has been halted while archeologists investigate further.