London, United Kingdom – A pro-Palestine academic who was planning to travel to the United Kingdom has been denied entry because the government says his “presence in the UK is not considered to be conducive to the public good”.

The UK Home Office cancelled Swedish national Andreas Malm’s Electronic Travel Authorisation (ETA) on Wednesday, an email seen by Al Jazeera shows.

The decision came a week before Malm was due to appear on a panel organised by the British socialist magazine Tribune in London. Huda Ammori, cofounder of Palestine Action – which the UK has proscribed as a “terrorist” group – is also due to appear on the panel, which will be chaired by Hala Hanina of Palestine Deep Dive. Malm told Al Jazeera that he believes his ETA was cancelled because he was due to appear on the panel.

He has contacted the Home Office for an explanation but is yet to receive a response. “I have been going regularly to the UK for decades. My position on Palestine has always been public,” Malm said, adding that his latest visit to the country was in May.

“I haven’t said anything in public about Palestine during these intervening months or written anything about it. The only thing that could have caused this [latest UK decision] is that I was due to be on a panel on Wednesday evening, where I would talk to Huda Ammori of Palestine Action,” he said.

Malm told Al Jazeera that he used an ETA to visit the UK in May, which allowed him to travel to the country again later in the year without seeking reauthorisation. He said he had received no indication from the Home Office that his ETA was at risk of being cancelled before receiving an email on Wednesday confirming that it had been revoked.

In its email, the Home Office told Malm that if he wishes to visit the UK, he needs to apply for a visa, after which the office will “consider your circumstances in more detail” before making a decision. However, the government website states that the processing time for a standard visitor visa is three weeks, meaning Malm would not receive it in time for next week’s panel even if his application were approved.

Travellers from countries whose nationals do not require a visa to visit the UK generally need an ETA. These include countries in Europe, the United States and Canada, among others.

Al Jazeera contacted the Home Office to ask for clarification on the cancellation of Malm’s ETA and whether it was connected to the event he planned to attend next week. They had not replied at the time of publication.

The cancellation of Malm’s ETA comes amid a wider crackdown on pro-Palestine activists by the UK government, something that began under then-Prime Minister Keir Starmer. Starmer, a former human rights lawyer, was prime minister when the government proscribed Palestine Action last year.

The move classified the campaign group as a “terrorist” organisation under UK law, placing it on the same legal list as groups such as al-Qaeda and ISIL (ISIS). The proscription has been condemned by rights groups, including Amnesty International.

Most recently, Irish novelist Sally Rooney’s books were withdrawn from sale in the UK this month due to her public support for Palestine Action.

“What this is about is constantly diminishing the room for [the] exchange of opinion and ideas and painting people with a brush of illegitimacy, that you’re beyond the pale, you’re not allowed to say what to think,” Malm told Al Jazeera.

“This is a drift towards authoritarianism that didn’t begin with me and it’s not going to end with me either. This is just one more small step in a long slide into the abyss of authoritarianism that we have in the UK and other countries, too. If I’m now being deemed a threat to the public good because I’m supposed to have a conversation with someone from Palestine Action, this is guilt by association. Where does it stop?”Gareth Dale, reader in political economy at Brunel University of London, told Al Jazeera that the Home Office’s decision suggests the UK government intends to continue suppressing free speech under Prime Minister Andy Burnham.

“Andreas Malm is one of the world’s foremost campaigners on the two defining issues of our times – climate breakdown and the genocide in Palestine. Barring him from entry to the UK represents a monstrous attempt by the Burnham government to suppress free speech,” Dale said.

“Typical of bureaucratic tyranny, no reason was given for the ban; it is cynical and Kafkaesque. As Malm has committed no crime, we are left guessing as to the motives. Burnham cultivated the impression that his government would be turning a new leaf, but instead it is replicating Starmer-era authoritarianism.”