ATHENS, Greece — Wildfires intensified across southern Europe on Wednesday with a round-the-clock battle to protect the perimeter of Greece’s third-largest city and at least three deaths reported in Spain, Turkey and Albania.

Firefighters were struggling to tame blazes in several countries in southern Europe, including Albania, Greece, Montenegro, Spain, and Turkey.

Wildfires briefly shut the Dardanelles Strait to shipping on Monday evening, as extreme heat and strong winds fueled blazes across the Mediterranean.