Dozens of people dressed in black and wearing balaclavas blocked the road at the port of Dover in Kent, forcing closures in both directions on Saturday morning.Kent police said they were were in attendance and engaging with the protest, which the Port of Dover described as a “public order incident”. No arrests were made during the incident. Responsibility for the demonstration appears to have been claimed by an anti-immigration group with links to the far right.The behaviour of the participants and the travel disruption they have caused has been condemned by the government. Traffic in and out of the port on the A20 was stopped, causing delays of up to 30 minutes and four miles of congestion, according to National Highways.Videos shared online showed a large number of masked people in black marching on the road in a large group as lorries waited in traffic next to police cars.By lunchtime, the protesters had dispersed and access roads to the port were “free flowing”, according to the Port of Dover. Ferry operators pledged to put those who had been delayed by the disruption on to the next available sailings.Masked people on the road in Dover. Photograph: Ay_audits/YouTubeThe number of people involved was not immediately clear. One livestreamer estimated he was marching with hundreds of people but police did not give an official estimate.Social media videos showed demonstrators linking arms in a blockade across the A20 and chanting “stop the boats”and “England till I die.”A group called Patriot Platform, which styles itself as having “a fierce love for our homeland”, claimed responsibility for the blockade.The far-right activist Tommy Robinson, whose real name is Stephen Yaxley-Lennon, reposted videos of the blockade, highlighting a live stream of the protest that directed viewers towards Patriot Platform.In his post, Robinson encouraged more to join, saying: “Get there to support them.”In another post, he wrote: “Simultaneously at different locations across Dover patriots have mobilised to close down the port. There are 3 plus locations that patriots have shut down so far with many more planned to be closed. People wanted action I’m guessing there are 100,000s of men willing to fill their shoes.”Map including DoverThe founder of Patriot Platform, Danny Thomas, also known as Danny Tommo, wrote on social media “live Dover somethings [sic] happening” and posted a live stream.In a video posted on 2 September, he told his followers he was meeting with “a huge group [of] top, proper patriots” to prepare for a message he was planning to send to the government.