A Republican member of the US House of Representatives says US envoy for Iran, Rob Malley, may be taking advantage of the Ukraine crisis to give Iran whatever it wants in the Vienna talks.

In a tweet on Wednesday, Claudia Tenney asked, “Is Robert Malley really trying to use the Ukraine Crisis as cover to give the radicals in Iran everything they've been asking for?” in the negotiations to revive the 2015 JCPOA (Joint Comprehensive Plan of Action) which the US left in 2018.

“That's the allegation and if true, it would be illegal”, she stressed, adding that “any deal with Iran must be submitted to Congress for review and approval; that’s the law”.

After Malley gave a classified briefing to members of Congress on talks in Vienna in February, Tenney said that his briefing had left her with "more questions than answers" and demanded the envoy testify openly to give details of what the US was “offering” in Vienna.

Gabriel Noronha, Former Special Advisor for the Secretary's Iran Action Group in the Trump administration in a series of tweets on Wednesdayquoted State Department, National Security Council and European Union unnamed officials as having authorized him to reveal that Malley is preparing to make concessions to Iran that are damaging to US national security.