Downing Street has refused to condemn controversial past remarks on pregnancies, eugenics and race reportedly made by a new adviser.
Labour said Andrew Sabisky should be sacked for suggesting black people had lower average IQs than white people and compulsory contraception could prevent “creating a permanent underclass”.
No 10 did not officially confirm his appointment or any role he may have.
The SNP and Liberal Democrats also said Mr Sabisky should go.
Mr Sabisky, appointed after the PM’s chief adviser Dominic Cummings called for “misfits and weirdos” to apply for jobs in Downing Street, has been contacted by the BBC for comment.
When asked on Monday, Downing Street did not comment on the remarks attributed to Mr Sabisky.
Boris Johnson’s spokesman added: “The prime