Iran may be cleaning up a suspected nuclear-weapons development site to fool U.N. inspectors, Western officials briefed on satellite intelligence said Wednesday.

The International Atomic Energy Agency twice tried to visit the Parchin site last month to assess its suspicions that Iran has been conducting explosives tests aimed at developing atomic weapons, The Wall Street Journal reported. Tehran twice rebuffed the requests.

In recent days, senior Iranian officials have said Tehran is reviewing the IAEA's request to visit Parchin and probably will grant a visit in the coming months. But the officials briefed on the satellite imagery tell the Journal they fear Iran is scrubbing any evidence linking Parchin to nuclear-weapons development, believed to be from their pre-2003 weapons program, by sanitizing the site.

We better get there sooner rather than later, said a European official briefed on the intelligence.

Two of the diplomats told the Associated Press the images suggested that crews at Parchin may be trying to erase evidence of tests of a small experimental neutron device used to set off a nuclear explosion. A third diplomat could not confirm that but said any attempt to trigger a so-called neutron initiator could only be part a nuclear weapons effort.

The diplomats said they suspect a cleanup drive because some of the vehicles at the scene appeared to be haulage trucks and other equipment suited to carting off potentially contaminated soil, the AP reported.

Iran has been the target of sanctions from the U.S. and others who charge it is pursuing nuclear weapons. On Wednesday, Foreign Minister Koichiro Gemba said Japan is in final stage talks with the U.S. on cutting its imports of Iranian crude oil. For months, Japan has sought an exemption from U.S. sanctions on Iran, which it says will damage its own economy. Gemba would not say when or by how much Japan will reduce its imports of Iranian oil, citing a possible destabilizing impact on commodities markets.

IAEA Director General Yukiya Amano hinted at concerns over Parchin this week in Vienna when he told the agency's board of governors that there was disturbing activity at the site.