Iranians have marked the 22nd anniversary of the U.S. downing of an Iranian passenger jet with a ceremony at the site where the plane crashed.

Family members of the 290 people killed were among those who gathered in Persian Gulf waters Saturday, where they laid flowers in memory of Flight 655 victims.

A statement from President Mahmoud Ahmadinejad was read at the ceremony.  He called the downing a "tragic human catastrophe" that was "not an understandable incident" but a "declaration of war against humanity."

The USS Vincennes shot down the passenger plane on July 3, 1988, shortly after the aircraft took off from the Iranian city of Bandar Abbas for Dubai in the United Arab Emirates.

The U.S. said it mistook the airliner for a hostile Iranian fighter jet.

The U.S. paid Iran more than $100 million in compensation as part of a 1996 settlement.

Some information for this report was provided by AP.