A strong showing by far-right candidate Marine Le Pen in Sunday's French presidential election would cause major problems, the head of the International Monetary Fund said Thursday.

"It would certainly unveil major disorder and the risk of dislocation," IMF Managing Director Christine Lagarde told CNBC during an interview at this week's meeting of the foundation and the World Bank in Washington.

Lagarde was speaking of the possibility of the National Front leader winning enough votes to qualify for a May 7 runoff by the top two vote-getters on Sunday.

Though Le Pen's standing in the polls has been fading recently, the prospect of a victory by the right, and the accompanying sentiment to get France out of the European Union, is one that Lagarde does not find encouraging.

"First of all, I think the (EU) project itself has protected us from the horrors of war, and we need to keep that in mind even for the younger generations which have not known any of that," she said. "But we were at our throats for centuries."

"The fact that we have had nearly 70 years of peace and amicable and constructive relationships is a jewel, and it needs to be secured," she added.

Lagarde did not predict which way the election would go, but did say she will be voting.

On other issues, her outlook is considerably sunnier.