Iran's foreign minister said on Saturday that accusations about activity at its Parchin military site were "lies" spread by opponents of its landmark nuclear deal with world powers clinched last month.
A prominent US think-tank on Friday questioned Tehran's explanation for activity at its Parchin military site visible in satellite imagery, saying the movement of vehicles did not appear related to road work.
"We said that the activities in Parchin are related to road construction," Foreign Minister Mohammad Javad Zarif was quoted on Saturday as saying by the IRNA state news agency.
"They (opponents of the deal) have spread these lies before. Their goal is to damage the agreement," he added.
The US-based Institute for Science and International Security (ISIS) said this week that Iran might be sanitizing its Parchin military site, where some countries suspect experiments may have taken place in a possible atomic weapons program. Iran denied it, saying it was part of road works near the Mamloo Dam.
"Commercial satellite imagery does not support the Iranian explanation," the think tank said in a statement. "ISIS analyzed commercially available satellite imagery taken on July 12, 19, and 26, 2015 but did not find any visible signatures related to road work on the road near the dam."
It said it would make little sense for Iran to "park vehicles three kilometers south of the dam and at the one site that would create intense concern and suspicion about Iran's intentions to comply with the recently negotiated (deal)."
Parchin is a site to which the UN nuclear watchdog, the International Atomic Energy Agency (IAEA), requested access as part of the July 14 nuclear accord between Iran and six major powers, which include the United States. ISIS suggested Iran could be engaged in cleanup work before IAEA inspectors arrive.
Attempts to sanitize the site could complicate the work of the IAEA, whose job it is to judge whether Iran's past atomic activity was linked to developing weapons, including through access to Parchin.
"There is no support in the imagery for the Iranian explanation," ISIS new analysis said. "Iran's explanation appears to be that the vehicles at the suspect site were there inadvertently, but this explanation strains believability."
The speaker of Iran's parliament also dismissed the think-tank's suggestions.
"This is an artificial dispute to distract the world. There are some movements at Parchin but trying to expand those activities to the military facility and making a fuss about it is like some fairy tale," Ali Larijani was quoted on Saturday by the Fars news agency as saying.
"Israelis are not happy about the deal and they will do anything to stop it," he added.
Prime Minister Benjamin Netanyahu has been pushing US lawmakers to oppose the nuclear agreement, which he considers a threat to his country's survival.
Some pro-Israel groups have been spending millions of dollars on an advertising campaign to persuade members of the US Congress to reject the deal in the autumn.