Downing Street has refused to clarify if Boris Johnson agrees with eugenics or whether black people are less intelligent than white people in wake of the controversial appointment of a new aide to the Prime Minister.

Pressed repeatedly on the views ascribed to Andrew Sabisky, Mr Johnson’s deputy spokesman simply said the PM’s “views are well-documented” and declined to comment on “individual appointments”.

Mr Sabisky was drafted in to No 10 after its chief strategist Dominic Cummings called for "misfits and weirdos" to apply to advise the Conservative Government.

The 27-year-old researcher is reported to have said -

*Black Americans have a lower average IQ than white Americans and were more likely to have an “intellectual disability”.

*"One way to get around the problems of unplanned pregnancies creating a permanent underclass would be to legally enforce universal uptake of long-term contraception at the onset of puberty. Vaccination laws give it a precedent, I would argue.”

*“I am always straight up in saying that women’s sport is more comparable to the Paralympics than it is to men’s.”

*The benefits of a purported cognitive enhancer, which can prove fatal, were "probably worth a dead kid once a year".

Calls have been made for Mr Johnson to sack Mr Sabisky.

One Government adviser told BuzzFeed News: “Hiring this imbecile is an insult to those who came before, which is a minor point I know but, Jesus wept, it makes me ashamed.”

Jon Trickett, Labour’s Shadow Cabinet Office Minister said: “There are really no words to describe Boris Johnson’s appointment as one of his senior advisers a man who is on record as supporting the forced sterilisation of people he considers not worthy. He must of course be removed from this position immediately.”

It is understood special advisers are prepared to boycott meetings where Mr Sabisky is present and refuse to reply to any emails he sends.

As the row intensified Nicola Sturgeon, the First Minister tweeted: "These are really not acceptable headlines for any government to be generating [or allowing to be generated]. They need to get a grip fast and demonstrate some basic but fundamental values in the terms of our public debate."

Ian Lavery, the Labour Chairman, said: "It is disgusting that not only has No 10 failed to condemn Andrew Sabisky's appalling comments but also seems to have endorsed the idea that white people are more intelligent than black people.

"Boris Johnson should have the backbone to make a statement in his own words on why he has made this appointment, whether he stands by it, and his own views on the subject of eugenics."

His colleague, Rebecca Long-Bailey, a leadership candidate, added: "We’ve got a Prime Minister who once published an article saying black people “are at the other pole” in terms of IQ. It’s no accident that Johnson has hired someone who supports eugenics."

Earlier, George Eustice, the Environment Secretary, when quizzed about Mr Sabisky’s appointment said it was a "matter for Dominic Cummings and No 10" when asked about the aide’s remarks on Sky News.

At the regular morning meeting of political reporters in Downing St, Mr Johnson’s spokesman repeatedly refused to answer questions about whether or not the PM agreed with Mr Sabisky’s views.

Asked about the new aide, he said: “I’m not commenting on individual appointments.”

When asked repeatedly about whether Mr Johnson agreed with Mr Sabisky’s reported views, the spokesman insisted: “The PM’s views are well-publicised and well-documented.”

When asked what these were, he repeated his answer.

Pressed on whether Mr Johnson would condemn such views, the spokesman said: “The PM’s views on a whole range of topics are well-publicised.”

Asked what Mr Johnson’s views were on eugenics, he repeated his views were well-documented but when challenged that they were not, he gave the same answer.

Asked several other questions on the subject, the spokesman said he “appreciated the persistence” but would “not be commenting further on this”.

When it was pointed out Grant Shapps, the Transport Secretary, made clear the Government did not share Mr Sabisky’s views, he was asked if this was the Government’s position but reporters were told Mr Shapps was speaking as the Transport Secretary.

When it was suggested the most well-documented comment of Mr Johnson on black people was calling them “piccaninnies,” the spokesman said the PM’s views were well-documented.

Meanwhile, No 10 insiders insisted Mr Johnson did not support eugenics but the he has courted controversy with his views on IQ in the past.

In a speech in 2013 he said any discussion about equality had to take account of the fact that 16 per cent of "our species" had an IQ below 85 while around two per cent had an IQ above 130, adding: "The harder you shake the pack, the easier it will be for some cornflakes to get to the top."

In 2000, while Mr Johnson was editor of the Spectator, the magazine carried an article from columnist Taki which said: "On average, Orientals are slower to mature, less randy, less fertile, and have larger brains and higher IQ scores. Blacks are at the other pole, and whites fall somewhere in the middle, although closer to the Orientals than the blacks."

Geneticist and broadcaster Dr Adam Rutherford also criticised Mr Sabisky's comments, writing on Twitter: "Like Cummings, he appears to be bewitched by science, without having made the effort to understand the areas he is invoking, nor its history."

He said the "moral repugnance" of the remarks was "overwhelming", adding: "I am all for scientifically-minded people advising Government. In fact, I am all for scientists advising Government. From this perspective, Sabisky, and indeed Cummings, look bewitched by science without doing the legwork.

"Instead, this resembles the marshalling of misunderstood or specious science into a political ideology. The history here is important, because this process is exactly what happened at the birth of scientific racism and the birth of eugenics."

Eugenics is the study of or belief in the possibility that the qualities of human beings can be improved by either discouraging people from having babies who are deemed to have genetic defects or undesirable inheritable traits or encouraging others to have babies who are deemed to have desirable inheritable traits.