image source, Nigel Glynnimage captionChoppy waters were seen at Vias in Hérault, where a man died

At least seven people have died after drowning in rough Mediterranean seas in the south of France, authorities say.

They were swept out to sea while swimming off seven beaches – despite warnings of dangerous choppy waters.

The seas were stirred up by storms and high winds.

Five people, in their 60s and 70s, died at five beaches in Hérault, in the south west. Another two men, aged 58 and 71, drowned at two beaches in the Bouches-du-Rhône, further east.

Emergency services in Hérault say they tried to save 12 people drowning off beaches at Agde, La Grande-Motte, Marseillan, Serignan and Vias. Seven were rescued but five died.

"I cannot understand how people got into the water when the seas were rough. It's a dramatic day for our region," said Jordan Dartier, the mayor of Vias, where one man drowned after reportedly falling from rocks.

Hérault's fire and rescue service had urged people to avoid swimming.

"Choppy seas are making water activities dangerous," it tweeted in the afternoon, with a video of waves crashing into the shoreline.

Two swimmers drowned off beaches at Cassis and La Ciotat in the Bouches-du-Rhône after being dragged out to sea, local media reported.

People did not understand the dangers of underwater currents, local fire chief Aurélien Manenc told broadcaster LCI.

"The water is warm, you think you are going to have fun, and quickly you are pulled towards the open sea and towards the bottom, and you are exhausted and trying to come back – this is what causes drowning or the beginning of drowning."

By late afternoon, police officers in Hérault were evacuating any beaches without life guards.

An orange weather alert is in place in the region, warning of storms and flooding.

"Wednesday 15 September will remain a black day for the Hérault coast," wrote local newspaper Midi Libre.