The European Union has turned down Iran’s offer to allow selected ambassadors accredited to the UN nuclear watchdog to visit two nuclear installations while the United States, Britain, France and Germany were not even invited on the trip.

China, ahead of President Hu Jintao’s state visit to the United States next week, said that it would be “difficult” for its ambassador to the International Atomic Energy Agency (IAEA) in Vienna to go on the proposed tour.

“The Vienna representative is still in China right now, so it will be difficult for him to go to Iran,” Foreign Ministry spokesman Hong Lei told a news briefing, without elaborating.

Just hours later, Russian Foreign Minister Sergei Lavrov told reporters in Moscow that such a visit could never replace regular inspections from the IAEA or talks with major powers on Iran’s disputed nuclear program, echoing the EU position.

“Such a visit should in no way at all be seen as a substitution for IAEA inspections,” Lavrov said, though he said the invitation deserved attention. He did not give a clear indication of whether Russia would agree to the tour.

Several UN Security Council resolutions have urged Iran to allow unrestricted inspections to defuse mistrust in Tehran’s stance that it is enriching uranium only for electricity and other peaceful purposes, not for nuclear weapons.

Without the European Union, China and possibly even Russia, Tehran’s trip proposal could collapse before Istanbul talks next week between Iran and the so called P5+1 group — the five permanent members of the Security Council along with Germany.

The West suspects Iran is trying to develop bomb-making capability under the cover of a declared civilian nuclear energy program. Russia and China have more complicated positions, and have watered down UN sanctions on Tehran adopted since 2006.

Moscow says the concerns about Iran’s nuclear program are justified and has called on Tehran to allay the worries. But Russia has also warned Israel and the United States that pushing Tehran into a corner could spark conflict in the Middle East.

Some diplomats say the Iranian tour proposal appears to be a negotiating ploy designed to drive a wedge between the major powers, while buying time to keep stockpiling enriched uranium.

But analysts that if that was the aim, it had failed.

“If that is what they were hoping to do, and probably they were, yes, it has failed,” said David Hartwell, IHS Jane’s Middle East and North Africa.

“There is widespread perception, certainly in the West, that this was a bit of a gimmick or public relations exercise.”

Diplomats said that Russia and China were being discouraged by Western officials from joining the tour and that Moscow and Beijing probably would not want to stand alone among big powers on the tour, especially ahead of Hu’s trip to the United States.

“This (China’s apparent rejection) is most likely related to President Hu Jintao’s visit to the United States, showing that China respects the United States’ position,” said Shi Yinhong, international relations expert at Renmin University in Beijing.

“China would also feel there is no point in them going if the EU and Russia also don’t.”

Like Moscow, Beijing has backed UN Security Council resolutions leaning on Iran to suspend enrichment activity in exchange for trade and other incentives, but has opposed unilateral sanctions imposed by Europe and the United States.

“Given the pressure the EU and others have put on them to politely decline the invitation, I would be very surprised if either of them would have said yes,” one European diplomat said on condition of anonymity.