VIENNA — On Thursday Iran’s envoy to the U.N. nuclear agency declined to commit to nuclear transparency measures that were part of a preliminary deal Tehran and world powers reached in April, deflecting U.S. demands to implement such provisions.

The United States urged Iran to implement the so-called Additional Protocol, which allows more intrusive access to Iranian sites, and Code 3.1, which requires from Iran early notification of the construction of any new nuclear facilities.

“These are the issues still under discussion and I believe we should wait to see the final text… and before that, we cannot prejudge anything,” Reza Najafi told reporters.

He added that Iran and the powers could seal a final deal by their self-imposed June 30 deadline, despite lingering disputes over the capacity of Iran’s uranium enrichment program, the extent of U.N. inspections and sanctions relief for Tehran.Iran has long denied Western suspicions that it has used its declared civilian nuclear energy program as a front for developing the ability to make atom bombs. To prevent any such outcome, the powers want Iran to accept unfettered inspections.

Laura Kennedy, U.S. envoy to the International Atomic Energy Agency in Vienna, told a session of the IAEA’s 35-nation governing board that it “remains critical for Iran to implement the provisions of Modified Code 3.1 … without delay”.

Kennedy also said it was important for Iran to implement the IAEA’s Additional Protocol, which allows U.N. inspectors under specific circumstances to visit Iranian sites with as little as two hours’ notice.

The Additional Protocol also permits the U.N. watchdog to collect environment samples like soil that can yield information on nuclear activities years after they have taken place.

Kennedy further said Iran had still not resolved longstanding IAEA questions about the “possible military dimensions” (PMD), mainly before 2003, of its nuclear program.

Najafi reiterated Tehran’s stance that some of the IAEA’s documents supporting concerns about PMD are intelligence fabrications. He also repeated that there will be little progress in the IAEA’s inquiry into Iran’s nuclear past unless the agency stops using these documents.

He referred to a case related to a former CIA officer who was convicted in January of leaking classified information to a reporter about a failed U.S. effort to undermine Iran’s nuclear program, which it says is entirely peaceful.

“We can discuss new practical measures provided that the inauthentic documents and information would be put aside,” Najafi said. The IAEA has said it carefully reviews information provided for its investigations and takes nothing at face value.

Iran and the powers — the United States, Russia, China, France, Britain and Germany — reached a framework deal on April 2 in Switzerland and are seeking to strike a broader settlement by June 30 under which Iran would curb its nuclear program in exchange for relief from economic sanctions.