Calls are growing for President Joe Biden's climate czar John Kerry to be investigated and to resign over accusations that he told Iran about Israeli military operations while serving as Secretary of State under former President Barack Obama.

"This is something that deserves a Senate investigation," Sen. Marsha Blackburn, R-Tenn., told Fox News, adding that Kerry has "put our men and women in uniform at risk."

"This is something that is serious," Blackburn, a member of the Senate Judiciary Committee, said. "This is someone who has served our nation at very high levels, that had information, whether as a senator or as Secretary of State and knew what was happening on the diplomatic and military front, to give that information to someone who is an adversary is something of tremendous concern to me."

The outcry over Kerry comes after Iranian Foreign Minister Mohammad Javid Zarif claimed in a leaked audiotape that while Kerry was secretary of state, he revealed more than 200 operations that Israel had conducted against Iranian targets. 

Kerry has also reportedly met with Zarif as a private citizen after leaving office, which is raising concern about what he may have told him and other Iranian officials. 

In a statement posted to Twitter Monday, Kerry called the allegations being made about him "unequivocally false."

"I can tell you that this story and these allegations are unequivocally false," Kerry said while retweeting posts by Washington Post reporter John Hudson concerning the conservative backlash over the reports from Iran. "This never happened, either when I was Secretary of State or since."

As U.S. Special Presidential Envoy for Climate, Kerry's post is a Cabinet-level position that wasn't subject to Senate confirmation. 

Morgan Ortagus, the spokesperson for the State Department under former President Donald Trump, told Fox News' "Fox and Friends" Tuesday that Zarif is Iran's "chief propagandist" but there are a "lot of problems" with Kerry's conversations with the key Iranian official. 

"Joe Biden did an interview with PBS a few years ago where he talked about the fact that John Kerry and Zarif used to talk to each other on John Kerry's cell phone," said Ortagus. "When I worked with Secretary (Mike) Pompeo, you always (went) through the State Department operation center for calls between foreign ministers, between leaders so that way there is a transcript and people know what's being said."

Kerry also has a "pattern of undermining Israel," said Ortagus. "There is some very, very odd pattern of behavior where John Kerry seems to be beholden to the Iranians and works at every inch he can against Israel."

Two lawmakers have called for Kerry to resign. Sen. Dan Sullivan, R-Alaska, said on the Senate floor that "it’s become clear … that our adversaries, whether Beijing or Iran, like it when John Kerry is in charge of foreign policy and national security. Why? Because they know how to use him to their advantage." 

Rep. Mike Gallagher, R-Wis., agreed, tweeting that Kerry should resign if Zarif's claims turn out to be true. 

Meanwhile, Mort Klein, president of the Zionist Organization for America, told Fox News that there should be an "immediate and thorough investigation" into Kerry, and Brian E. Leib, the executive director for Iranian Americans for Liberty, said that if Zarif's allegations turn out to be true, they are "grounds for treason" charges against Kerry. 

State Department Spokesman Ned Price declined to speculate on the authenticity of the tape, but said that the governments involved were "speaking publicly, on the record."

The Kerry controversy has surfaced while the Biden administration is in negotiations to rejoin the Joint Comprehensive Plan of Action, also known as the Iran nuclear deal. Trump pulled the United States out of the deal. 

Blackburn has introduced a bill to stop the Biden administration from reentering the Iran nuclear deal unless the matter is submitted to the Senate for a vote first. 

"What worries me a good bit, is how these despotic regimes are emboldened to push back against the United States," she said. "We need to send a strong message to our adversaries, and this new axis of evil of Russia, China, Iran, and North Korea that we are going to push back on them and we will not let them win."

• Nikki Haley to Newsmax TV: Kerry 'Disgusting,' Should Be Off Security Council
• Leaked Recording of Iran's Top Diplomat Offers Blunt Talk