This article is more than 4 years old

This article is more than 4 years old

Jeremy Corbyn and John McDonnell are to speak at a Momentum conference that will run at the same time as Labour’s official party conference in Liverpool, although organisers deny it is intended to be a rival event.

Momentum, a group that is not affiliated to the Labour party but supports Corbyn’s leadership, will run the free four-day event concurrently with the autumn conference in September. In a tweet, the national organiser, James Schneider, said: “It’s not a rival conference. It’s part of the fringe at Labour conference. Complimentary [sic], not rival.”

The event, called The World Transformed, will feature Corbyn, the shadow chancellor, McDonnell, shadow health secretary, Diane Abbott, and shadow defence secretary, Clive Lewis.

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There has been criticism of Corbyn’s billing alongside the Marxist writer Richard Seymour. Under a shared Facebook post, Seymour is alleged to have written of an Israeli journalist, “fuck him, they should cut his throat”. The author of a book about the Labour leader, titled Corbyn, is also said to have criticised the Falklands veteran Simon Weston, who suffered severe burns, by posting on Facebook: “If he knew anything, he’d still have his face.” Screengrabs of the comments have been posted on the Guido Fawkes blog.

Seymour, who blogged frequently for the Guardian until two years ago, wrote in 2014 that the Green party could attract Labour voters by showing its “dark side”.

“The problem with the Green party is that it is too nice,” he wrote. “They don’t hate, and if leftwing politics in this country needs anything it is a dose of rigorous hate.”

Other participants in the event at the Black-E community arts venue in Liverpool will include the artists Jake and Dinos Chapman, Guardian journalist Owen Jones, former Channel 4 news journalist Paul Mason and film-maker Ken Loach.

Jeremy Corbyn talks about Momentum event, The World Transformed.

In a promotional video for the event, Corbyn said: “I’m going to be there, because I want to see a world transformed. All those people, with all those ideas, ambitions and energy, are going to be there as well.

“Come along and join us – you’ll have a great experience. Doing things together benefits us all, educates us all, makes us strong, and does change the world.”

Workshops at the event will explore subjects such as the future of trade unions, universal basic income and “What can a left government do?”

Momentum said it would be “a space of inclusive and respectful debate, discussion and ideas where attendees have the opportunity to contribute to a radical, positive vision for the 21st century”. Organisers have booked out hostels in Liverpool for attendees to stay in.