PARIS Heavy storms caused chaos across France at the weekend as thousands of holiday makers prepared to depart for their summer break, causing blackouts and floods and felling a tree in Strasbourg which killed 11 people.

The country's road information service on Saturday "strongly" advised people to put off the annual summer exodus until Sunday after torrential rain overnight on Friday blocked roads.

In Strasbourg, 11 people died and 17 were seriously injured after a violent storm blew a huge plane tree onto a crowd at an open air theater late Friday.

The eleventh victim succumbed to injuries in hospital on Saturday.

Around 200 rescue workers were rushed to the scene, where a field hospital was set up to attend a further 67 spectators suffering from shock or minor injuries, the regional authorities said.

Over 12 hours of incessant downpour produced traffic chaos in and around Paris early on Saturday and led to 150 people being temporarily evacuated from their homes near the Eiffel Tower.