The State Department says the U.S. has had at least one direct conversation with Iran over allegations of a brazen assassination plot on U.S. soil.

State Department spokeswoman Victoria Nuland said Thursday there's been "direct contact" between the U.S. and Iran. She gave no details.

Separately, a U.S. official says the contact was made through Iran's United Nations mission in New York. The official spoke on condition of anonymity to describe sensitive diplomacy.

The two nations have no diplomatic relations and any direct contact is rare.

The U.S. says Iran was behind a foiled plot to kill the Saudi Arabian ambassador to the U.S. Iran denies it.