A Labour MP has rubbished claims that there was a heated exchange between Boris Johnson and Sir Keir Starmer after Prime Minister’s Questions.

The pair had clashed in the Commons after the Prime Minister accused the Labour leader of repeatedly calling for the UK to stay in the European Medicines Agency after Brexit, suggesting such a move would have hampered the country’s Covid-19 vaccine rollout.

Sir Keir described the remarks as “complete nonsense” but Hansard, the official record of Parliament, shows that in January 2017 he questioned why the UK would want to leave the body and that it should be something retained as part of the Brexit process.

The Opposition leader and Mr Johnson were seen walking out of the Commons together following the terse session and continued their conversation while standing just outside the chamber.

According to eyewitnesses quoted by The Sun, the political rivals were seen having a “heated discussion” about the Prime Minister’s EMA remarks, allegedly resulting in Sir Keir being “led away” by ally and Labour whip Chris Matheson.

But Mr Matheson called the eyewitnesses’ claims “absolute bollocks”, adding: “There was a brief chat and then Keir and I left together.

“Nothing more to it than that.”

A Labour source said: “They had a perfectly reasonable conversation as they often do after PMQs.”

Asked about the alleged altercation, Mr Johnson’s press secretary Allegra Stratton said: “I have seen the reports but I haven’t seen the Prime Minister since he went to the Chamber so I can’t confirm or deny that.”