Bloomberg said the US was pushing to open "a special investigation" into Iran’s past nuclear work, but "it’s not gaining traction among the international officials who can make it happen."
The financial news provider said it had obtained documents and interviewed diplomats who attended a meeting between US officials and the International Atomic Energy Agency (IAEA) in Vienna last week, Presstv Reported.
"American officials have been ratcheting up pressure at the International Atomic Energy Agency in recent weeks, threatening new sanctions and advocating for more aggressive inspections," Bloomberg said.
"However, the efforts are falling flat," it said, citing three diplomats who participated in the meeting.
It’s a rare pushback for the US at the IAEA ... the episode illustrates the rising difficulty American officials face in convincing allies to follow the US on Iran," it added.
During the private meeting held on January 20 and attended by 70 diplomats assigned to the IAEA, the participants heard what hawkish US national security adviser John Bolton called “substantial evidence” that Iran had lied to IAEA inspectors.
“There is a sense that the administration is frustrated that their campaign to renegotiate the deal isn’t working,” said Ellie Geranmayeh, a senior fellow at the European Council on Foreign Relations.
“What we see is the US maximum pressure campaign is heating up even further,” she added.
The diplomats said the fresh US allegation was based on an analysis by the Foundation for Defense of Democracies and the Institute for Science and International Security, which used data supplied by Israel.
Israeli Prime Minister Benjamin Netanyahu has on several occasions drawn international ridicule for his allegations about Iran’s “secret” nuclear activities.
Last September, Netanyahu went to the UN to show pictures of an alleged Iranian nuclear weapons storage site, which turned out to be a carpet cleaning factory, with the IAEA ignoring the claim.
“There has been a concern that the US and some other countries want to precipitate an inspection crisis,” Geranmayeh said. “But there’s been resistance to this. The deal’s stakeholders feel they have a good grip on what’s happening in Iran.”
The US has been trying to coerce the Europeans into following its lead and withdrawing from the 2015 nuclear deal with Iran, which President Donald Trump renounced in May.
Since the US left, the deal’s remaining powers -- China, France, Germany, Russia and the UK -- have struggled to provide the sanctions relief promised when Iran agreed to nuclear caps.
The Europeans are currently trying to put a special purpose vehicle designed to protect companies from US sanctions into operation, but are facing Washington's threats of retribution for any trade with Tehran.
Bloomberg cited the diplomats in Vienna as saying that "while they will continue engaging with the US, they want to avoid provoking a scenario that will escalate into a new crisis with Iran."
One envoy said the US was forcing the IAEA to "rehash 20-year-old information" which had been settled down by the nuclear agency, warning that it could shut the doors to diplomacy and lead to "tragic consequences".