The death toll from severe rainstorms that lashed parts of Greece, Turkey and Bulgaria increased to 14 on Wednesday after rescue teams in the three neighbouring countries recovered seven more bodies.

A flash flood at a campsite in northwestern Turkey near the border with Bulgaria killed at least five people — with three found dead on Wednesday — and carried away bungalow homes. Rescuers were still searching for one person reported missing at the campsite.

Another two people died in Istanbul, Turkey's largest city, where Tuesday's storms inundated hundreds of homes and workplaces in several neighbourhoods.

The victims in Istanbul included a 32-year-old Guinean citizen who was trapped inside his basement apartment in the low-income Kucukcekmece district, Turkish broadcaster HaberTurk TV reported. The other was a 57-year-old woman who died after being swept away by the floods in another neighbourhood, the private DHA news agency reported.

The surging floodwaters affected more than 1,750 homes and businesses in the city, according to the Istanbul governor’s office. They included a line of shops in the Ikitelli district, where the deluge dragged parked vehicles and mud into furniture stores, destroying the merchandise, DHA reported.

The floods also engulfed a parking area for containers and trucks on the city's outskirts where people found safety by climbing on top of the roof of a restaurant, Turkish media reports said.

In Greece, record rainfall caused at least three deaths near the central city of Volos and in Karditsa, further to the west, according to the fire service. Three people were reported missing.

Authorities banned traffic in Volos, the nearby mountain region of Pilion and the resort island of Skiathos, where many households remained without electricity and running water on Wednesday. Traffic was also banned in another two regions of central Greece near Volos, while the storms were forecast to continue until at least Thursday afternoon.

In Bulgaria, a storm caused floods on the country’s southern Black Sea coast. The bodies of two missing people were recovered from the sea on Wednesday, raising the overall death toll to four.

Video showed cars and camper vans being swept out to sea in the southern resort town of Tsarevo, where authorities declared a state of emergency.

Most of the rivers in the region burst their banks and several bridges were destroyed, causing serious traffic problems.

Tourism Minister Zaritsa Dinkova said that about 4,000 people were affected by the disaster along the entire southern stretch of Bulgaria’s Black Sea coast.

“There is a problem transporting tourists because it is dangerous to go by coach on the roads affected by the floods,” she added.