Donald Trump’s new acting head of US intelligence was likened to a "far-right colonial officer” and said he wanted to “empower” Europe’s right-wing while serving as an ambassador.

Richard Grenell, the current US ambassador to Germany, was announced as the acting national director of intelligence on Wednesday in a sign that the president may be planning on stamping his personal political views on US spy agencies.

Although Mr Trump described the ambassador as having represented the US “exceedingly well”, Mr Grenell is said to be deeply unpopular in Germany following controversial interviews with Fox News and the far-right news website Breitbart.

In 2018, the ambassador angered politicians within weeks of taking office after he said he wanted to “empower other conservatives throughout Europe” and warned German companies against doing business with Iran.

“Grenell does not behave like a diplomat, but like a far-right colonial officer,” Martin Schulz, a former leader of Germany's centre-left Social Democratic Party, said in response to the comments.

“What this man is doing is unique in the history of diplomacy,” Mr Schulz added.

“If the German ambassador in Washington would say that he is there to strengthen the Democrats, he would be expelled straight away.”

Mr Grenell also faced criticism for describing Austrian Chancellor Sebastian Kurz, who formed a coalition with the country’s far-right Freedom Party, as a “rock star”.

Ambassadors are generally expected to remain politically neutral in the country they are serving.

In an article by the German newspaper Der Spiegel, the staunch Trump loyalist was condemned by sources over his troubled relationship with the country.

Although the 30-odd sources who had come into contact with Mr Grenell were not willing to be quoted by name, it was reported that the majority of them described him as “a vain, narcissistic person who dishes out aggressively, but can barely handle criticism.”

“They also say Grenell knows little about Germany and Europe, that he ignores most of the dossiers his colleagues at the embassy write for him, and that his knowledge of the subject matter is superficial,” the article added.

As the acting director of national intelligence, Mr Grenell will be in charge of overseeing and integrating the US intelligence community and will advise on matters of national security.

The ambassador, who is thought to be the first openly gay man to serve in the role, has never worked for an intelligence agency.

Following the president's announcement, a number of national security experts criticised the decision to appoint Mr Grenell to the role.

“[Trump] just named the most political - and abrasive - US ambassador to what is supposed to be the least political - and undoubtedly delicate - roles [sic],” Ned Price, who served as a special assistant to Barack Obama, wrote on Twitter.

“Just as he's no longer pretending to respect rule of law, Trump has dropped the charade that he has any use for intelligence.”

Mr Price quit the CIA after more than 10 years of service in 2017 in protest against the Trump administration.

Susan Hennessey, a senior fellow in national security at the Brookings Institution, warned Mr Grenell was “utterly incompetent”.

“This should frighten you. Not just brazen politicisation of intelligence, but also someone who is utterly incompetent in an important security role. The guardrails are gone,” Ms Hennessey said.