Bafta has said it is taking a security breach “very seriously” after a social media prankster gatecrashed the final acceptance speech for best film award.

A man, believed to be a YouTuber, joined director Christopher Nolan and the Oppenheimer team on stage as they accepted the prestigious prize at the end of Sunday night’s ceremony at the Royal Festival Hall in London.

Dressed in a black suit and tie, the gatecrasher stood beside actor Cillian Murphy as Nolan’s wife and producer Emma Thomas delivered a speech on behalf of the team.

Bafta said in a statement: “A social media prankster was removed by security last night after joining the winners of the final award on stage – we are taking this very seriously, and don’t wish to grant him any publicity by commenting further.”

The man may have initially evaded suspicion as he walked on to the stage as Thomas encouraged the rest of the Oppenheimer cast to join them, saying: “Where are you? Come on, all of you.”

The epic biopic about J Robert Oppenheimer, the theoretical physicist described as the father of the atomic bomb, scored seven awards in total at the ceremony.

British filmmaker Nolan picked up the best director award, his first Bafta following previous nominations for Inception and Dunkirk.

Christopher Nolan and Emma Thomas after winning the Best Film award for Oppenheimer
Christopher Nolan and Emma Thomas after winning the Best Film award for Oppenheimer (Ian West/PA)

Irish star Murphy also landed his first Bafta for his titular role in the film while Robert Downey Jr won best supporting actor for his role as Lewis Strauss, head of the Atomic Energy Commission.

During his speech, Murphy told Nolan: “Thank you for always pushing me and demanding excellence because that is what you deliver time and time again.”

He said Oppenheimer was a “colossally knotty character”, adding: “We have a space to debate and interrogate and investigate that complexity and it’s a privilege to be a part of this community with you all.”

The award show, which was hosted by Doctor Who star David Tennant, secured an average audience of 3 million with the show reaching 3.8 million viewers at its peak.