British Ambassador to the U.S. Kim Darroch speaks during an annual dinner of the National Economists Club at the British Embassy, Oct. 20, 2017 in Washington, D.C. Getty

London -- The British government was hunting Monday for the source of a leak of diplomatic cables from Britain's ambassador in Washington that branded President Donald Trump's administration "dysfunctional" and "inept." British officials are embarrassed by the publication of Kim Darroch's unflattering assessment, but more alarmed that sensitive confidential information has been leaked, possibly for political ends.

British International Trade minister Liam Fox, who is visiting Washington this week, told CBS News partner network BBC radio that he would apologize personally to Mr. Trump's daughter and advisor Ivanka Trump when he met her later Monday.

"I will be apologizing for the fact that either our civil service or elements of our political class have not lived up to the expectations that either we have or the United States has about their behavior, which in this particular case has lapsed in a most extraordinary and unacceptable way," he told the BBC.

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"Malicious leaks of this nature ... can actually lead to a damage to that relationship, which can therefore affect our wider security interest," added Fox.

British Foreign Secretary Jeremy Hunt said Monday that the ability to communicate frankly was "fundamental" to diplomacy.

"I've seen nothing to suggest hostile state actors were involved," said Prime Minister Theresa May's spokesman, James Slack.

Slack said May had "full faith" in Darroch, a long-serving diplomat, although she didn't agree with his characterization of the Trump administration.

He said ambassadors were hired to provide "honest, unvarnished assessments" of politics in the countries where they served, which didn't necessarily reflect the views of the British government.

What the cables said

In the leaked cables -- published in the Mail on Sunday newspaper -- Darroch called the Trump administration's policy toward Iran "incoherent, chaotic" and said there were doubts about whether the White House "will ever look competent."

"We don't really believe this administration is going to become substantially more normal; less dysfunctional; less unpredictable; less faction riven; less diplomatically clumsy and inept," one missive said.

The cables cover a period from 2017 to recent weeks.

After the cables were published, Mr. Trump said the ambassador "has not served the U.K. well, I can tell you that."

"We are not big fans of that man," Mr. Trump said.

U.K. political sabotage?

Officials in London believe the mole will be found among British politicians or officials, rather than overseas.

The leak is an embarrassment for outgoing prime minister May, who has sometimes clashed with Mr. Trump, and could make things difficult for Darroch, who is accused by some Brexit-backing U.K. politicians of a lack of enthusiasm for Britain's departure from the European Union.

The journalist who reported the leak, Isabel Oakeshott, is a strong supporter of Brexit.