Firefighters battled massive blazes tearing through forests across France and Spain Monday, as authorities warned of a fresh heatwave set to engulf the scorched French wine-growing region around the major city of Bordeaux.More than 325,000 people have fled their homes, mostly in the Gironde department, home to Bordeaux, as some of the worst forest fires in either country's history rage across southwest France and central Spain near Madrid.

France's fire has caused an unprecedented "pyrocumulonimbus" -- a giant fire cloud that creates its own winds and packs lightning that causes more blazes, said the National Firefighters Federation of France (FNSPF).

"It's a David-versus-Goliath scenario [...] at some point, we'll find a weak spot and strike there," said FNSPF spokesman Eric Brocardi.

French President Emmanuel Macron will hold a crisis cabinet meeting to discuss the emergency on Monday morning.

Spanish Prime Minister Pedro Sanchez will visit fire-hit areas in Valencia, in the east of the country on Monday where firefighters are battling a new blaze and where 15,000 people have been forced to flee their homes.