British far-right activist Daniel Thomas has been arrested for allegedly using a knife to slash an inflatable dinghy being used by migrants trying to cross the English Channel.
A video posted online appeared to show Mr Thomas yelling "you're in English territory" toward the vessel, which had rescue service members aboard.
British police say Mr Thomas remains in custody, but is yet to be charged.
A British far-right activist known for leading protests against migrants crossing the English Channel in small boats has been arrested for allegedly slashing a dinghy at sea.
Daniel Thomas, 37, appeared to be involved in an incident showcased in a video posted to social media where he used a knife to pierce the inflatable vessel.
The boat was empty of migrants, but at least one rescue service member was aboard at the time, while Mr Thomas yelled "you're in English territory" towards their direction.
"You're not using these boats, no more migrants in our country," Mr Thomas allegedly said in the video.
"This is England, this is not France … No more of this, we've taken too many."
After piercing the vessel's inflatable exterior, Mr Thomas then appeared to tell the rescue workers to "get off the boat" while his own vessel began to move away.
Hampshire and Isle of Wight Constabulary said on Thursday, local time, that a 37-year-old man has been arrested the previous evening on suspicion of criminal damage with intent to endanger life and endangering the safety of a vessel.
The constabulary said he remained in custody on Thursday. British police do not identify suspects by name until they are charged.
Mr Thomas, who goes by the nickname Danny Tommo, is a longtime associate of far-right activist Stephen Yaxley-Lennon, also known as Tommy Robinson.
Robinson has preceded political controversy in Australia in recent months after he interviewed One Nation leader Pauline Hanson, who blamed the end of the White Australia policy for migration issues.
A month earlier, in an interview with former Today Show host turned podcaster Karl Stefanovic, Robinson claimed Australians were losing their culture, that traditional values were under attack, and that the established news outlets was lying to its audience.
Patriot Platform, a group Mr Thomas founded, is behind recent protests in which masked, black-clad men tried to stop migrants reaching the United Kingdom.
Earlier this month, masked demonstrators blocked the port of Dover, in south-east England, and tried to stop migrants from being taken ashore in Portsmouth on the country's south coast.
Successive UK governments have attempted to stop people — more than 41,000 last year — making the journey across one of the world's busiest shipping lanes.
The issue has been depicted as a crisis by politicians including Nigel Farage of the hard-right party Reform UK, and has been used as a rallying point by anti-immigration activists.
Prime Minister Andy Burnham's centre-left government says stepped-up law enforcement cooperation between Britain and France has helped reduce the number of people making the crossing so far this year by more than 40 per cent compared with 2025.