Iran said on Thursday it had "forced" a US submarine to surface as it was crossing the strategic Strait of Hormuz in the Persian Gulf, a claim which was promptly denied by the Americans, reported the AFP news agency.
Admiral Shahram Irani, the commander of Iran's navy, told state TV the USS Florida nuclear submarine was "approaching and passing in complete silence" when it partly entered Iranian waters.
An Iranian submarine then forced it to "surface and cross the strait", he said, adding that Tehran would raise the matter with "international authorities".
In a subsequent Twitter statement, the US Navy's Bahrain-based 5th Fleet said the claim was "absolutely false" and "represents more Iranian disinformation".
The "US 5th Fleet continues to operate wherever international law allows", it added.
The reported incident comes a day after the US Navy sailed its first drone boat through the strategic Strait of Hormuz.
The trip by the L3 Harris Arabian Fox MAST-13, a 13-meter speedboat carrying sensors and cameras, drew the attention of Iran’s Revolutionary Guard, but took place without incident, said Navy spokesman Cmdr. Timothy Hawkins.
The Strait of Hormuz, a crucial waterway for global energy supplies, has often been a site of tense encounters between Americans and Iranian forces.
In early December, an Iranian patrol boat tried to temporarily blind US Navy ships in the Strait of Hormuz by shining a spotlight toward the vessels and crossing within 150 yards of them.
Last August, an Iranian ship seized an American military unmanned research vessel in the Gulf but released it after a US Navy patrol boat and helicopter were deployed to the location.
Two months earlier, three vessels controlled by the Iranian Revolutionary Guard Corps (IRGC) buzzed two American ships at what the US military called “dangerously high speed”.
The Islamic Republic has threatened more than once to close the Strait of Hormuz, with the United States warning Iran in response that any attempt to close the strait would be viewed as a "red line" -- grounds for US military action.