Bourse and Bazaar | AFP: President Donald Trump lashed out at�former secretary of state John Kerry for his meetings with Iran's foreign�minister after the Obama-appointee had left office.

"John Kerry had illegal meetings with the very hostile Iranian Regime which�can only serve to undercut our great work to the detriment of the American�people," Trump said on Twitter late�Thursday.

"He told them to wait out the Trump Administration!" he said, ending his�Tweet with the word "BAD!"

Kerry, who negotiated the 2015 Iran nuclear deal which Trump scrapped this�year, said during a tour to promote his new book "Every Day is Extra" that he�had met Iranian Foreign Minister Mohammad Javad Zarif "three or four times"�since he left office and Trump had entered the White House.

Without commenting on the legality of such meetings, the current US�Secretary of State, Mike Pompeo, accused his predecessor of "actively�undermining US policy."

"What secretary Kerry has done is unseemly and unprecedented," said Pompeo,�who is seen as an anti-Iran hawk.

"This is a former secretary of state engaged with the world's largest State�sponsor of terror and according to him... he was telling them to wait out this�administration."

A spokesman for Kerry said there was nothing improper about his conduct.

"Secretary Kerry stays in touch with his former counterparts around the�world just like every previous Secretary of State," the spokesman said in a�statement.

"And in a long phone conversation with Secretary Pompeo earlier this year�he went into great detail about what he had learned about the Iranian's view."

"No secrets were kept from this administration," the statement said,�accusing Kerry's successor of "political theatrics."

Straight Talk

Asked by conservative radio host Hugh Hewitt�on Wednesday�if he had offered�Zarif advice on how to deal with Trump's decision to withdraw from the pact,�he replied: "No, that's not my job.

"What I have done is tried to elicit from him what Iran might be willing to�do in order to change the dynamic in the Middle East for the better.

"I've been very blunt to Foreign Minister Zarif, and told him look, you�guys need to recognize that the world does not appreciate what's happening�with missiles, what's happening with Hezbollah, what's happening with Yemen,"�he added, echoing the current administration's denunciation of Tehran's�"malign" influence.

Conservative commentators immediately leapt on the act as evidence of�"treason," with some calling for Kerry to go to prison.

Asked by a Republican lawmaker during a congressional hearing about the�so-called shadow diplomacy, Manisha Singh, an assistant secretary of state,�said�Thursday: "It's unfortunate if people from a past administration would�try to compromise the progress we're trying to make in this administration."

State Department spokeswoman Heather Nauert added: "I've seen him brag�about the meetings that he has had with the Iranian government and Iranian�government officials. I've also seen reports that he is apparently providing,�according to reports, advice to the Iranian government.

"The best advice that he should be giving the Iranian government is stop�supporting terror groups around the world."