Gavin Williamson has been branded the most ignorant and incapable education secretary in the UK’s history after he appeared to confuse Marcus Rashford with the England rugby player Maro Itoje, who is also black.

The cabinet minister, who is widely tipped for demotion at a long-awaited reshuffle some Westminster insiders think could take place on Thursday, made the apparent gaffe in an interview with the Evening Standard.

Williamson was asked by the newspaper if he had met Rashford, the Manchester United and England footballer who has led a campaign to extend free school meals.

“We met over Zoom and he seemed incredibly engaged, compassionate and charming but then he had to shoot off,” the education secretary said, adding: “I didn’t want to be the one that was holding him back from his training.”

The Standard reported that Williamson’s team later clarified he had not in fact met Rashford, but was instead talking about Itoje, the Saracens and England rugby player who has campaigned to improve access to laptops and the internet for children unable to attend school during the Covid pandemic.

Williamson said in a short statement that he made a “genuine mistake” and “conflated the issues” of laptops and school meal campaigns that had both come up during the interview, adding that he had “huge respect” for Rashford and Itoje’s “effective and inspiring campaigns”.

Rashford’s spokesperson confirmed he had not met the education secretary on a Zoom call and that his requests to collaborate with those in power had often been rebuffed. “Maro and Marcus are two incredibly successful young black men, but there is little more they have in common,” they added.

The footballer himself tweeted that the two stars’ different accents “could have been a giveaway”, with an emoji of someone crying with laughter.

Itoje also posted: “Due to recent speculation I thought it was necessary to confirm that I am not Marcus Rashford … And whilst we are here my name is not Mario either!! Just a simple Maro Itoje will do … Much love, Marcu … I mean Maro Itoje.”

Williamson, who in the same interview said he had enough “grit and determination” to weather the storm that has brewed over his political future for a year, faced a deluge of criticism from opposition politicians.

David Lammy, the shadow justice secretary, called it “appalling” and tweeted asking how Williamson had confused the two sports stars. “You must be the most ignorant, clueless and incapable education secretary in the UK’s history,” he said.

Angela Rayner, the deputy Labour leader, posted: “According to Gavin Williamson, a black man from Wythenshawe who plays football for England looks the same as a black man from north London who plays rugby for England. The fact that Gavin Williamson remains in his job is a daily reminder of how mediocre white men rise and rise.”

The Match of the Day presenter Gary Lineker struggled to believe Williamson had made such a gaffe, tweeting: “Surely not.”

Boris Johnson’s press secretary said she was unaware of the education secretary’s comments when asked on Wednesday afternoon if they amounted to racism.