The ministry said the Unesco-listed archaeological site would close from midday to 5pm, with temperatures expected to reach 43°C today and tomorrow.

The first heatwave of the year in Greece, regularly hit by searing summer temperatures, is due to peak over those two days, and the ministry said the measure could be extended.

The climate crisis and civil protection ministry has warned of a very high risk of fires in the Attica region that surrounds Athens.

Schools will remain closed in several regions of the country today and tomorrow, including in the capital, while the work ministry has advised public sector employees to work from home.

The Acropolis was also forced to close in July last year during a two-week heatwave unprecedented in its duration.

A record number of almost 4 million visitors flocked to the site last year, with its popularity boosted in part due to tourists arriving on cruise ships calling in at the port of Piraeus near Athens.