WASHINGTON — U.N. nuclear experts accused Iran of attempting to conceal nuclear weapons work.

According to diplomats accredited to the International Atomic Energy Association, the nuclear watchdog of the United Nations, satellite images show what appears to be crews and vehicles cleaning up radioactive evidence of tests of a device used to create a nuclear explosion, the Associated Press reported.

The diplomats said Wednesday that they suspected a cover-up because the vehicles evident in the images appear to be trucks used to cart off contaminated soil.

On the same day, the IAEA’s chief said that while Iran had opened some facilities to inspections that had verified their peaceful purposes, there are indications that other sites may be engaged in activities related to the development of nuclear weapons.

“There may be other facilities which are not declared, and we have the indication or information that Iran has engaged in activities relevant to the development of nuclear explosive devices,” Yukiya Amano told CNN.  

In a statement Thursday, the United States, China, France, Russia, Germany and Great Britain jointly called on Iran to grant inspectors access to the site, located at the Parchin military facility southeast of Tehran, Reuters reported. A report from the IAEA last year said that construction developments at Parchin are “strong indicators of possible weapon development.” Iran has maintained that its nuclear endeavors are for peaceful purposes.

The latest revelation comes just days after President Obama and Israeli Prime Minister Benjamin Netanyahu met to discuss the potential nuclear threat from Iran.

In his address to the AIPAC Policy Conference on Monday, Netanyahu intimated that Israel cannot wait much longer to stop a nuclear Iran.

“We’ve waited for diplomacy to work, we’ve waited for sanctions to work, none of us can afford to wait much longer,” he said. “As prime minister of Israel, I will never let my people live in the shadow of annihilation.”