Large parts of the Czech Republic were left without electricity on Friday following a major blackout, the country's grid operator reported.

"At the moment we can confirm that there is a power outage in our electricity grid," Hana Klimova, a spokeswoman for the grid operator CEPS, told AFP.

"The outage has affected a greater part of the Czech Republic," she added.

Prime Minister Petr Fiala described it as an "extraordinary and unpleasant" situation in a post on X.

What do we know about the Czech blackout?

Czech Transport Minister Martin Kupka said train lines in five out of the country's 14 districts had been halted, including in the capital, Prague.

Shortly after the first reports of the blackout, CEPS said that the cause was a fallen power line.

It added that the electricity supply had been returned to the majority of the impacted areas.

Prague's subway network was temporarily knocked offline, but lines A and C were restored within just 15 minutes, and line B was restored within half an hour.

Czech police said on X they had "no information suggesting this is a cyber/terror attack."

E.ON, the company that runs the grid in the southern part of the country, said its supply had not been affected. Neighboring Poland also said it had not registered any problems.

Why are blackouts significant?

The Czech blackout comes several months after an even bigger blackout sent Spain and Portugal into darkness for several hours.

That incident was the result of a "voltage surge," but there had been fears at the time that the Iberian peninsula had fallen victim to a cyber attack.

Friday's blackout also comes after a recent heat wave hit Europe. Electricity becomes particularly important to run fans or other cooling systems.

However, Prague on Friday recorded temperatures of only around 25 degrees Celsius (77 Fahrenheit), down from the 34 degrees recorded on Thursday.

Edited by: Kieran Burke