VIENNA — Satellite images of an Iranian military facility appear to show trucks and earth-moving vehicles at the site, indicating an attempted cleanup of radioactive traces possibly left by tests of a nuclear-weapon trigger, diplomats told The Associated Press on Wednesday.

The assertions from the diplomats, all nuclear experts accredited to the International Atomic Energy Agency, could add to pressure on Iran over its nuclear program, which Tehran insists is for peaceful purposes.

While the U.S. and the EU are backing a sanctions-heavy approach, Israel has warned that it may resort to a pre-emptive strike against Iran’s nuclear facilities to prevent it from obtaining atomic weapons.

Two of the diplomats said the crews at the Parchin military site may be trying to erase evidence of tests of a neutron device used to set off a nuclear explosion. A third diplomat could not confirm that but said attempts to trigger a so-called neutron initiator could only be in the context of trying to develop nuclear arms.

In a November report, an IAEA report said Parchin appeared to be the site of experiments with explosives meant to initiate a nuclear chain reaction.

It did not mention a neutron initiator, but a separate section said Iran may have experimented with a neutron initiator. In contrast, the intelligence information shared with the AP by the two diplomats linked the high-explosives work to setting off a neutron initiator.

The November report said that “if placed in the center of a nuclear core of an implosion-type nuclear device and compressed, [a neutron initiator] could produce a burst of neutrons suitable for initiating a fission chain reaction.”

U.S. intelligence officials say they generally stand by a 2007 intelligence assessment that asserts Iran stopped comprehensive secret work on developing nuclear arms in 2003. But Britain, France, Germany, Israel and other U.S. allies think such activities have continued past that date, a view shared by the IAEA. Asked for comment, Ali Asghar Soltanieh, Iran’s chief delegate to the IAEA, told the AP he would not discuss any nuclear issues until after he delivered his statement to the agency’s 35-nation board meeting Thursday. IAEA officials also said they could not comment. Attention most recently focused on Parchin several days ago, when senior IAEA officials spoke of unexplained activities without saying what they could be and said an inspection of buildings there was taking on added urgency.

They declined to go into detail but said radioactive traces could be left by other material. Tehran said that an agreement outlining conditions of an IAEA inspection of Parchin must first be agreed on — a move dismissed by a senior international official as a delaying tactic.

The diplomats and officials spoke ahead of a meeting of the IAEA board Thursday focusing on Iran’s defiance of U.N. Security Council demands to end uranium enrichment.

Officials did not detail the text agreed upon, but the U.S., Britain, France and Germany wanted a joint statement that takes Iran to task for defying U.N. Security Council resolutions and cooperate with an IAEA probe.

A Western diplomat told the AP that Russia and China sought more moderate language.

Printed on Thursday, March 8, 2012 as: Evidence indicates Iran trying to develop nuclear weapons trigger