Emmanuel Macron will urge Donald Trump to keep America engaged in Syria for the long run on Tuesday as the pair meet for face-to-face talks in the White House.

The French president is expected to warn that new terrorist threats could emerge if the US disengages from the country as it remains locked in civil war.

The White House has confirmed a “way ahead in Syria” will be discussed in what officials predicted will be a “full and free airing of points of view” with Mr Macron.

America’s Syrian policy is up in the air as Mr Trump balances his instinctive opposition to foreign intervention with a determination to police a “red line” over chemical weapons use.

Mr Trump said last month that US troops would withdraw from Syria “very soon”, only to be convinced by advisers to stay for the time being to defeat the last remaining Isil fighters.