Iran has called for the United States to apologize for allegations of an Iranian plot to assassinate the Saudi Ambassador to the U.S.

Iranian foreign minstry spokesman Ramin Mehmanparast said Tuesday that Iran has sent a letter to the U.S. seeking an apology.

The letter also calls for the U.S. to provide compensation for damages based on the U.S. allegations. It was sent through the Swiss Embassy in Tehran, which represents U.S. interests because the U.S. and Iran do not have diplomatic relations.

U.S. officials have accused two suspects of conspiring to carry out a $1.5 million plot by the Iranian Revolutionary Guard's elite Quds force to kill Saudi envoy Adel al-Jubeir by bombing a Washington restaurant.

Manssor Arbabsiar pleaded not guilty to the charges last week in a New York court. He is a naturalized U.S. citizen holding Iranian and American passports.

The second suspect, Gholam Shakuri, is at large, but is believed to be in Iran.

Iran has denied involvement in the case.