Ukip is expected to choose a controversial YouTube activist, who has been accused of triggering rape threats against a Labour MP, as a candidate if Britain takes part in the European elections, it has emerged.

A party selection process this weekend is likely to confirm the candidacy of Carl Benjamin, a self-styled free speech activist who has been banned from Twitter and some other platforms because of his views, Ukip sources said.

As with other parties, Ukip is preparing for the possibility that Brexit might be delayed beyond elections to the European parliament in May, meaning UK voters would have to elect MEPs.

Benjamin, who calls himself Sargon of Akkad after the ruler of a Mesopotamian empire, first became known for his anti-feminist commentary, and has also expressed controversial opinions on immigration, race and other issues.

In 2016 he tweeted “I wouldn’t even rape you” to the Labour MP Jess Phillips, in a message featuring the tag #feminismiscancer. Phillips said she subsequently received 600 rape threats.

Benjamin, who is among a trio of social media-based activists who joined Ukip last year, has previously used racially charged language, accusing alt-right critics during one live web interview of “acting like a bunch of niggers”. He added: “You think white people act like this? White people are meant to be polite and respectful to one another.”

In another discussion he argued that institutional racism was “actually good for the black community” in reducing levels of poverty and crime.

As well as being barred from Twitter, Benjamin has been removed from the crowdfunding website Patreon. It said this was because he had used hate speech.

Benjamin, who calls himself a “classical liberal”, still has a YouTube channel, where he has nearly 1 million subscribers. In one recent video he interviewed the far-right anti-Islam activist Tommy Robinson, who is an adviser to the Ukip leader, Gerard Batten.

During the chat Benjamin rejected the idea that the terrorist who killed 50 people in an attack on mosques in Christchurch, New Zealand, a week ago did so because he had been radicalised by far-right views spread via the internet.

“He was radicalised by visiting France and watching the results of mass immigration in France,” Benjamin said, arguing that such concerns were legitimate.

The attacker’s actions were “a terrible thing to do”, Benjamin said, adding: “But that doesn’t mean the things he’s seeing aren’t valid.”

Benjamin’s arrival in Ukip, alongside fellow YouTube activist Mark Meechan, also known as Count Dankula, and Paul Joseph Watson from the US conspiracy theory website Infowars, marked one of the early signs of Batten’s decision to shift the party’s focus.

Batten’s anti-Islam tone and policies, and his recruitment of Robinson, whose real name is Stephen Yaxley-Lennon, has led to an exodus of senior Ukip figures, including its former leader Nigel Farage.

David Lawrence from Hope Not Hate, which monitors hard-right groups, said: “Benjamin has a history of using vile racist terms and misogynist politics, so it’s hardly surprising he would stand for Ukip given how far right they’ve shifted over the past few years. They sound like the perfect fit.”

A party spokesman said: “Ukip will not comment on potential candidates for European parliament election lists. Ukip will provide a full slate of candidates in every region, and we will announce our candidate lists within the next fortnight, if a European parliament election is called.”