Donald Trump’s outspoken former adviser Steve Bannon has praised Boris Johnson and Tommy Robinson in the same interview, describing the Tory MP as being potentially “a great prime minister” and the far-right activist as a “force of nature”.

The US rightwing populist said he admired Johnson and that the former foreign secretary had “nothing to apologise for” after his controversial descriptions of fully veiled Muslim women in a newspaper column.

He said Johnson should continue to make similar points. He told the Sunday Times (paywall): “Boris just needs to be Boris – true to his nature and his calling – and I think he has potential to be a great prime minister, not a good one.”

Bannon has been in contact with Johnson since he resigned from government last month, although he added: “Any conversations I have with active political figures are confidential – I consider Boris Johnson someone who understands the physics in the ebb and flow of events. Those individuals are rare.”

On Robinson, Bannon said: “Tommy is not just a guy but a movement in and of himself now. He represents the working class and channels a lot of the frustration of everyday, blue-collar Britons … He is a force of nature – like Kanye [West] – not built to be managed.”

Robinson was jailed for contempt of court after he filmed outside Leeds crown court during a trial, but was released on bail this month after an appeal court ruled that he should face a retrial on technical grounds.

The row over whether it was appropriate for the Conservative party to refer Johnson to its own disciplinary processes continued through the weekend. On Thursday, the party said it had asked an assessor to review dozens of complaints that had been made after he compared women wearing the burqa to letterboxes and bank robbers.

The former Conservative minister Damian Green, an ally of Theresa May, said he feared Johnson was “being turned into a martyr by the alt-right”, which would be “a disaster for him and the Conservative party”.

He wrote in the Mail on Sunday: “I am particularly concerned by reports that President Trump’s sacked adviser Steve Bannon is forming a Europe-wide far-right campaign group – and has been in touch with Boris. I hope that no Conservative politician, including Boris, is taking advice from him about how the Conservative party should behave.”

Meanwhile, Tell Mama, the government-backed hate crime monitoring group, said there had been a surge in anti-Muslim abuse aimed at women wearing the hijab and niqab. It said the majority of niqab-wearing victims who had called Tell Mama’s helpline since the article appeared said the perpetrator either used phrases such as “letterbox” or referred to Johnson.

The secretary general of the Muslim Council of Britain, Harun Rashid Khan, said: “The impact of Boris Johnson’s comments is real and worrying, and indicates the importance of a full, transparent and independent investigation into his conduct, in particular given the lack of action in previous cases of Islamophobia in the party.”

A former aide to David Cameron accused Boris Johnson of “moral emptiness”, casual racism and “courting fascism”. Lord Cooper, a former pollster who worked for Cameron at No 10, said: “The rottenness of Boris Johnson goes deeper even than his casual racism and his equally casual courting of fascism. He will advocate literally anything to play to the crowd of the moment. His career is a saga of moral emptiness and lies – pathetic, weak and needy, the opposite of strong.”

Rightwing Tories continued to defend him. Jacob Rees-Mogg, leader of the party’s anti-EU right wing, criticised the prime minister for backing the investigation into Johnson’s remarks. Rees-Mogg said May had countenanced a “show trial” of Johnson because of her personal rivalry with him.

Johnson has returned from holiday but a close friend of his said he was “as likely to ride naked down Blackfriars cycle lane waving an EU flag” as he was to apologise. His father, Stanley, writing in the Sunday Telegraph, said his son was “spot on” in his comments on the burqa but should have gone further and called for a ban in certain circumstances.