That certainly is one possible conclusion to be drawn from what's happening at Parchin, an Iranian military base that western intelligence agencies have long suspected of carrying out A-bomb work.

Reuters:

Parchin, which Iran says is a conventional military complex, is at the centre of Western allegations that Iran has conducted experiments - possibly a decade ago - that could help it develop nuclear bombs. Iran denies any such ambition.

Last week, a U.S. think-tank published satellite images of Parchin which it said underscored concern that Iran is trying to destroy evidence of possible nuclear weapons-related research.

The Institute for Science and International Security (ISIS) posted the pictures on its website hours after the IAEA showed diplomats at a closed-door briefing similar images that Western envoys said indicated a clean-up at Parchin.

"The satellite imagery indicates that these activities include the use of water, demolishing of buildings, removing fences and moving soil," Amano told a news conference.

"These are some of the activities that we have observed through satellite imagery," he said, expressing concern that they could hamper the agency's efforts to find out what has been going on at the site, if and when it gains access.

Western diplomats say the buildings that appear to have been razed recently are small side buildings near the main structure that is of interest to the IAEA.

Negotiations have dragged on for a couple of years over giving the IAEA access to the Parchin site. As a signatory to the nuclear non-proliferation treaty, Iran is treaty bound to allow inspectors anywhere they ask - with some exceptions made for military bases and other top secret sites. The delay in allowing inspectors on the site should raise concerns about just what was being done at that site and if it relates to other nuclear work connected to bomb making.