Workers whistled and jostled with Macron's security guards while a burning tyre threw a cloud of black smoke across the site when the former economy minister visited the tumble-drier factory in his hometown of Amiens.

A Reuters photographer at the scene reported that some supporters of far right leader Marine Le Pen, who Macron will face in a May 7 runoff vote for the presidency, were mingled with the crowd.

Earlier, Le Pen, who is campaigning on an anti-globalisation platform, sought to upstage Macron with a surprise visit to the same factory.