Anti-Islam activist Tommy Robinson has had his account reinstated on social media platform X, formerly Twitter.
Robinson, whose real name is Stephen Yaxley-Lennon, was reinstated alongside political commentator Katie Hopkins.
A number of controversial figures have been allowed back on the platform since it was bought by Elon Musk last year.
In November 2022, Mr Musk - a self-styled "free speech absolutist" - announced a "general amnesty" to suspended accounts that had "not broken the law or engaged in egregious spam".
Research by BBC Monitoring found that of 1,100 reinstated accounts it examined, nearly 190 were promoting hate and violence.
X has also reinstated the controversial influencer and self-proclaimed misogynist Andrew Tate, whose accounts are banned by YouTube, Facebook, Instagram and TikTok.
Nick Lowles, chief executive of anti-hate campaigners Hope Not Hate, criticised the latest move by X.
"Reinstating Tommy Robinson and Katie Hopkins means Elon Musk is allowing hateful content and misinformation to take place on his watch on X/Twitter," he said.
The group said it would be writing to X to "make it clear the danger that their content poses".
Hopkins, a former LBC presenter and MailOnline columnist, has repeatedly attracted criticism for her views - including an incident where she compared migrants to cockroaches and another when she claimed that a photograph of a drowned three-year old Syrian refugee had been staged.
In 2017 she caused anger when she tweeted that there must be a "final solution" to dealing with terrorists following the Manchester Arena attack.
She later changed the term "final solution" to "true solution", describing the earlier version as a "mis-type".
Hopkins had more than one million Twitter followers before her permanent suspension in 2020. The ban was for violating the platform's hateful conduct policy but it did not, however, say which of her tweets had prompted the action.
Following her reinstatement Hopkins posted on X: "Thank you @elonmusk. And thank you to all the Twitter family who have brought Tommy & I back to @X.
"Know this. You are not alone. We are many. And we are stronger together. The fight back for your freedom is on."
Robinson founded the far right English Defence League, best known for protests against what it calls "radical Islam", but stepped down in 2013.
In July 2021 Robinson was ordered to to pay £100,000 in libel damages to a Syrian schoolboy who was filmed being attacked in a playground.
In two videos posted to Facebook, Robinson made a number of false accusations about the boy.
In November 2013, Robinson pleaded guilty to fraud, and he was subsequently jailed for 18 months.
He also has convictions for stalking, assault, using someone else's passport, using threatening behaviour and contempt of court.
Mr Musk and X have repeatedly proclaimed "freedom of speech, not reach" as a mantra, meaning that they intend to provide free speech for all - while simultaneously limiting the reach of offensive and misleading posts.
In practice, it hasn't always worked that way, and many accounts prone to spreading misinformation on the platform have access to X Premium (formerly Twitter Blue). For Premium subscribers the platform actually boosts their posts in the algorithm.
Thousands of accounts that were previously banned from Twitter have been reinstated since Mr Musk's takeover.
These include accounts with fringe views that were suspended for hateful conduct, accounts that shared health misinformation and anti-vaccine content during the Covid pandemic, and those that spread conspiracy theories about the 2020 US election.
Some of those accounts have since been resuspended by X for repeating past offences.
The BBC has approached X for comment.