A controversial left-wing streamer who once said America 'deserved' the September 11 attacks claims he has been barred from entering Britain.

Hasan Piker told followers he was blocked from traveling to London for a series of high-profile appearances because of his views on Israel and the Middle East.

Piker revealed the alleged travel ban during a lengthy livestream Sunday, saying British authorities denied his Electronic Travel Authorization (ETA), a permit that allows many Americans to enter the United Kingdom without applying for a visa.

'I've been banned from the UK,' Piker told viewers. 'I've been to the UK on numerous occasions, and all of the things they're complaining about now are things I've said before.'

The self-described socialist commentator said he had been scheduled to spend a week in Britain, including appearances at SXSW London, a live podcast event and a speaking engagement at the Oxford Union.

Piker described the decision as shocking and repeatedly questioned why British authorities had suddenly moved against him after years of allowing him to travel freely.

'It's f***ing ridiculous,' he told viewers.

The streamer later claimed he believed the decision was linked to allegations of antisemitism, which he strongly denied.

Piker accused pro-Israel organizations of wielding significant influence over British policy and suggested opposition to Zionism was increasingly being treated as grounds for exclusion from Western countries.

'Israel advocacy organizations have unbelievable amounts of power over what even the United Kingdom has to say and do,' Piker said. 'If you're an avowed anti-Zionist, your travel will be restricted.'

He also described the decision as evidence of a broader crackdown on dissenting political views.

'This is straight-up fascism,' Piker said. 'Being critical of Israel while combating antisemitism is not a good enough reason to bar someone entry into the country.'

British authorities have not publicly confirmed the reasons behind Piker's claimed ETA denial. 

Piker told viewers he only recently learned of his own alleged travel restriction and said he was exploring whether obtaining a traditional visa might still be possible.

'I genuinely did not think this would happen,' he said. 'We're moving into a very different timeline.'

As his livestream drew to a close, the usually combative broadcaster appeared stunned by the development, repeatedly returning to the same point.

'Bro, they banned me from the UK,' Piker said.

The controversy erupted just weeks after several Jewish organizations in Britain urged officials to prevent Piker from entering the country, citing remarks they viewed as antisemitic and supportive of extremist groups.

The Jewish Leadership Council and the Community Security Trust argued that Piker's presence in Britain would not be 'conducive to the public good,' pointing to comments he has made about Hamas, Hezbollah, Zionism and Orthodox Jews.

Labour MP David Taylor had also called on the Home Office to revoke permission for Piker's planned visit ahead of his scheduled SXSW London appearances.

Piker has generated controversy for years over inflammatory comments about American foreign policy and the Israeli-Palestinian conflict.

Among the remarks that continue to draw criticism is his statement that the United States 'deserved' the September 11 terrorist attacks because of its actions overseas.

He has also referred to Hamas as 'the lesser of two evils' when comparing the terrorist group with Israel.

Most recently, during an appearance on Pod Save America, Piker described the Republican Party as the 'biggest domestic terrorist' organization and the 'biggest terrorist internationally.'

Fox News reported how Piker was at protests outside an ICE facility in Newark, New Jersey this weekend where hecklers confronted him and accused him of being a 'fraud' and a 'grifter.'

Piker's uncle, The Young Turks founder Cenk Uygur, confirmed on Sunday that he too had been prevented from traveling to Britain.

'I've been banned from the UK. I tried to get on a flight to London to attend SXSW London and give a speech at Oxford. I've been banned for criticizing Israel,' Uygur wrote on X.

'Are we free anymore? This is oppression of Western citizens by our own governments on behalf of a different country!'

British Home Secretary Shabana Mahmood decided Uygur's presence would not be 'conducive to the public good.'

The report said concerns included whether his rhetoric following Hamas' October 7, 2023 attack on Israel could contribute to rising antisemitism.

The decision cited several factors, including statements critics argue echoed longstanding antisemitic tropes regarding Israeli influence over American politics.