Trump says Paris attack will influence France's election

President Donald Trump is taking the unusual step of weighing in publicly ahead of a foreign presidential election, predicting that the latest attack in Paris will have a "big effect" on voters there.

"Another terrorist attack in Paris. The people of France will not take much more of this. Will have a big effect on presidential election!" he tweeted.

On Thursday, an attacker in Paris used an automatic weapon to shoot officers in the center of the Champs-Elysees. One officer was killed, as was the gunman, and the Islamic State claimed responsibility.

Trump, in a break with his predecessors, has not been shy in casting terror attacks in political terms. In November 2015, he took to Twitter to blame France's strict control laws for an Islamic State terror attack at multiple sites in Paris and its suburbs that left 137 people dead.

And last year, he tweeted that he would "appreciate the congrats" for being right about the dangers of "radical Islamic terrorism" in the aftermath of the Florida nightclub shooting that left 49 dead. The shooter was a US citizen of Afghan descent.

The outcome of France's presidential election is being closely watched for signs that Europe is moving toward nationalist candidates who advocate the European Union's dissolution. The top two candidates from Sunday's vote in Paris will progress to a winner-takes-all May 7 runoff.

Trump was a supporter of the British decision to exit the European Union and has stated his preference for one-on-one trade and defence agreements with US allies.