John Kerry denies informing Iran of Israel's Syria strikes
Kerry came under fire after a leaked audio recording surfaced where Iran's Foreign Minister Mohamad Javad Zarif recalled an encounter with his former US counterpart.
In the recording, which Iran has admitted to being authentic, Zarif said Kerry informed him that Israel had attacked Iranian interests in Syria at least 200 times.
"I can tell you that this story and these allegations are unequivocally false. This never happened – either when I was secretary of state or since," Kerry tweeted.
The claims have led to calls for Kerry to resign from his role as the Biden administration's special envoy for climate.
In the US Senate, Republican lawmakers took aim at the former secretary of state, demanding answers about the allegations.
"People are talking about treason - and I don't throw that word around a lot," Republican senator Dan Sullivan was quoted by Politico as saying.
Nikki Haley, a former Trump administration envoy to the UN, also weighed in on the allegations. Haley demanded that President Joe Biden and Kerry "answer for why Kerry would be tipping off Iran, the number one sponsor of terror, while stabbing one of our greatest partners, Israel, in the back".
The US State Department is yet to issue an official statement on the issue, however spokesman Ned Price on Monday appeared to suggest that the information allegedly leaked by Kerry was already public knowledge.
"I would just make the broad point that if you go back and look at press reporting from the time, this certainly was not secret," Price told reporters.