David Albright and Paul Brannan of the Institute for Science and International Security, based in Washington, wrote in a report the April 9 image of the site at Parchin, about 20 miles southeast of Tehran, has raised suspicions Iran could be trying to clean out evidence of nuclear activity at the facility, CNN reported.
The image shows a stream of water coming from a building suspected of housing a chamber to conduct explosives testing for potential nuclear weapons, Albright and Brannan wrote.
The report also said items appear outside the building that were not evident in previous satellite images.
"The items visible outside the building could be associated with the removal of equipment from the building or with cleansing it. The stream of water that appears to emanate from the building raises concerns Iran may have been washing inside the building, or perhaps washing the items outside the building," Albright and Brannan wrote in their report.
The U.N. nuclear watchdog, the International Atomic Energy Agency, tried to visit Parchin twice last month. But Iran rejected the IAEA requests.
The IAEA said Iranian officials had said Tuesday Tehran is reassessing the request to allow a visit to Parchin.
Iran says its nuclear program is for peaceful uses only.