A man stormed the stage while the UK’s entry, SuRie, was performing at the Eurovision Song Contest.
SuRie was singing her song Storm when a man wearing a rucksack ran onto the stage, grabbed her microphone, and appeared to say: “Nazis of the UK media, we demand freedom.”
He was swiftly dragged off stage and SuRie continued performing the song.
SuRie has been given the chance to sing again as the show’s final performance but declined.
The invader is in police custody, the European Broadcasting Union said. He is understood to be a European citizen but not British.
The BBC said: “SuRie and her team are extremely proud of her performance and have together decided that there is absolutely no reason to perform the song again.”
The Eurovision 2018 final in Lisbon, Portugal, is being watched by an estimated TV audience of 200 million.
After the incident Graham Norton, who is presenting the UK’s coverage, said: “There was a stage invasion, SuRie coped incredibly well.
“I can’t stress enough what a brilliant job she did – she must have been terrified.”
Although SuRie was left without a microphone for about 10 seconds – during which she clapped along to the song – the music track continued with backing vocals.
The 29-year-old was praised on Twitter for her composure and ability to continue after the stage invasion.
Former work and pensions secretary Yvette Cooper said SuRie “pumped it up even better for being interrupted”.
TV presenter Scarlett Moffatt added: “Hope SuRie is ok, she is an absolute star.”
Performances from 26 nations should be finished by 22:15 BST, when voting will begin.
The voting is weighted so that half the points come from public telephone votes from viewers in each country, and half from a jury of musical experts in each nation.
The act with the highest overall points wins, and a result is expected at about 23:30 BST.
Before becoming the UK’s Eurovision entry, SuRie worked with Belgian contestants as a backing singer in 2015, and as a music director last year.
The Harlow-born singer is classically-trained and went to the Royal Academy of Music.