VIENNA: Iran's nuclear chief on Monday accused the United States of seeking to undermine a landmark 2015 deal with major powers, calling on the UN watchdog to resist Washington's "unacceptable demands", reports AFP.

"The American administration's overtly hostile attitude and actual foot-dragging policies and measures aimed at undermining the nuclear deal... are contrary to the letter and spirit" of the accord, Ali Akbar Salehi said in Vienna.

He hit out at the US envoy to the United Nations, Nikki Haley, for making a "host of unjustifiable, peculiar demands" in talks with IAEA chief Yukiya Amano in Vienna last month.

These reportedly included that the IAEA inspect military sites in Iran, something which officials in Tehran have rejected. US Energy Secretary Rick Perry told the Vienna meeting that Washington would "not accept a weakly enforced or inadequately monitored deal".

But Haley's demands are "far beyond the purview of the JCPOA and its collectively negotiated and well-defined provisions," Salehi said, referring to the full name of the deal, the Joint Comprehensive Plan of Action.