Foreign Secretary Boris Johnson. Spencer Platt / Getty LONDON — Members of President Donald Trump's government reportedly do not want to deal with British Foreign Secretary because "they think he's a joke."

White House officials, as well as diplomats across Europe, are baffled by Prime Minister Theresa May's decision to make Johnson Britain's foreign secretary and struggle to take him seriously, according to senior sources cited by The Times Rachel Sylvester.

Figures in President Trump's White House "don’t want to go anywhere near Boris because they think he’s a joke," diplomatic sources have told Sylvester, while a current government minister said: "It’s worse in Europe. There is not a single foreign minister there who takes him seriously. They think he’s a clown who can never resist a gag."

"The French think Boris is totally unreliable, the Germans think he’s a liar and the Italians think he’s dangerous," one Conservative MP told Sylvester.

"He is undermining our ability to negotiate internationally and degrading our position abroad. The foreign secretary is supposed to enhance Britain’s reputation but all over the world Boris is making matters worse."

Johnson, who went up against May in the race to succeed David Cameron as prime minister last summer, has been accused of insulting foreign counterparts and demeaning his own office on numerous occasions since becoming foreign secretary last year.

At the end of last year, Italian minister Carlo Calenda said he felt insulted by Johnson after the Tory minister suggested Italy should push for Britain to remain in the single market otherwise it would be forced to sell less prosecco. Frank-Walter Steinmeier, now German president but formerly Johnson's counterpart, reportedly told colleagues that he couldn't stand to be in the same room as the former London mayor.

Civil servants in the Foreign Office are "horrified" by Johnson's lack of discipline and professionalism, Sylvester adds.

"It’s all about managing Boris, not respecting him," she quotes one Whitehall source as saying. "He’s got no concentration span so it’s difficult to have a detailed discussion with him. The whole thing is completely ramshackle for someone who is supposed to be so clever. He doesn’t know what he thinks so he flies by the seat of his pants."

Earlier this summer Steve Bullock, a former UK negotiator to the EU, told Business Insider he was "extremely glad" that he didn't have to work for Johnson during his time as a civil servant, describing him as "the rear-end of a pantomime horse."

Bullock added: "He's really interesting because you can kind of see that he sees it as a game with winners and losers. And the objective is just to win. He doesn't seem to be aware of the consequences."

A spokesperson for May said the prime minister still has "full confidence" in the foreign secretary and added: "I’m not going to comment on a newspaper column. The prime minister meets the foreign secretary regularly. They have a good relationship."