Iran shot down two US navy drones outside its airspace in the Gulf, ILNA news agency quoting a top military commander as saying on Sunday.
The head of Guards' air force, Amir Ali Hajizadeh, said on January 2 that his forces had shot down two drones after they "violated" Iranian territory.
But on Sunday, General Gholam Ali Rashid, the deputy chief of staff of Iran's armed forces, said the unmanned aircraft were shot down outside the airspace of the Islamic republic.
"We have to say that these planes were shot down outside Iran's airspace, which means outside our FIR (Flight Information Region), in the Persian Gulf by the air force of the Sepah (Guards)," Rashid said.
He did not explain why the Guards struck at the drones outside Iran's airspace.
Soon after the initial report from Hajizadeh, Western media quoted US officials as rejecting the statement.
But on Saturday, the commander of the Guards' naval forces, Ali Fadavi, said the drones would be put on public display, saying the two unmanned vehicles were "among the most modern US navy drones" and had a long-range capability.
The US navy's Fifth Fleet is based in Bahrain, just across Gulf waters from Iran.
The US military and Central Intelligence Agency regularly use drones to launch missile strikes in Afghanistan and in Pakistan's lawless tribal belt, but do not generally confirm attacks.
Iranian commanders have repeatedly threatened to block navigation through the strategic Strait of Hormuz, which links the Gulf to the Indian Ocean, if the Islamic republic comes under attack.
Forty per cent of the world's oil supplies passes through the strait.
Iran's Revolutionary Guard Corps, target of a series of US sanctions, was set up as a force to defend the 1979 Islamic revolution from internal and external threats.
Washington has targeted the Guards with sanctions in a bid to hike pressure on Tehran over a controversial nuclear programme which Iran says is entirely peaceful but which world powers suspect is aimed at building an atomic bomb.