French President Emmanuel Macron Tuesday pledged an "unprecedented operation" against drug trafficking in Marseille during a surprise visit to the southern port city beset by gangland killings.

"In Marseille and other cities in France, we have launched an unprecedented operation to put a stop to drug trafficking and ensure republican order," Macron wrote on X, formerly Twitter, after arriving in the city to mark the launch of the operation which according to press reports will require the mobilisation of thousands of police.