Downing Street needs to examine its vetting process for staff to “prevent racists” working for Boris Johnson, a Conservative minister has said.

Andrew Sabisky left his job as a government adviser last night following an outcry over past comments had made about women and black people. 

The 27-year-old had once suggested black Americans have a lower average IQ than white Americans.

He also advocated enforcing the uptake of contraception to stop unplanned pregnancies creating a “permanent underclass”.

Kwasi Kwarteng, a business minister, said on Tuesday morning Sabisky’s remarks were “racist” and “offensive”.

“It’s been objectionable, offensive and he’s left the government. I think it’s unfortunate he was hired. He’s now left and we can now all move on,” he said.

Asked by BBC Radio 5 Live if the hiring process for Downing Street staff should be looked at, Kwarteng said: “Yeah, I think you’re right, we should prevent racists from coming into No.10.”

Kwarteng also said the “message has been clear” from government that Sabisky’s views were “totally unacceptable”.

But a spokesperson for the prime minister yesterday repeatedly refused to condemn Sabisky’s views or to say whether Johnson agreed with them.

Conservative MP Caroline Nokes, the chair of the Commons women and equalities committee, said she was “relieved” Sabisky had resigned, but criticised the “silence” from Downing Street.

She told BBC Radio 4’s Today programme on Tuesday morning: “I was disappointed that yesterday there was silence from Downing Street regarding [Sabisky’s] previous comments and it does seem that when the call went out for ‘misfits and weirdos’, that was exactly what Downing Street got.”

Nokes, a former minister, added: “I think [Johnson] needed to come out earlier and explain himself, he needed to apologise for those comments and unfortunately we had 48 hours of almost complete silence and no comment from Downing Street, who could have distanced themselves from his youthful comments at any point, but they chose not to do so.”