Two cars were set on fire after an explosion near a synagogue in southern France as authorities "step up security" at Jewish institutions.

A police officer was injured during the "clear criminal attack" on the Beth Yaacov synagogue in La Grande-Motte.

President Emmanuel Macron has vowed to "find the author of this terrorist act and protect places of worship".

Firefighters, police, and the gendermerie arrived at the scene at around 8.40am on Saturday morning.

Two cars were set on fire after an explosion near a synagogue in southern France as authorities "step up security" at Jewish institutionsGetty

France's Interior Minister Gerald Darmanin said the incident was "an obviously criminal act".

President Macron wrote on social media: "Thoughts for the faithful of the synagogue of La Grande-Motte and all the Jews of our country.

"Everything is being done to find the author of this terrorist act and protect places of worship.

"The fight against anti-Semitism is a constant battle, that of the united Nation."