The triple Olympic gold medallist "is hopeful to be back in competition for the relay events later in the swimming programme", according to a Team GB statement.

"Adam Peaty began feeling unwell on Sunday, ahead of his men's 100m breaststroke final," it said. "In the hours after the final, his symptoms became worse and he was tested for Covid early on Monday morning. He tested positive at that point."

Peaty, who was the two-time reigning 100m champion, was edged out into second by just 0.02 secs by surprise winner Nicolo Martinenghi of Italy in a thrilling race on Sunday. There was no suggestion at the time that Peaty was unwell.

"As in any case of illness, the situation is being managed appropriately, with all usual precautions being taken to keep the wider delegation healthy," Team GB added.

The British Olympic Association remains optimistic Peaty will recover in time for the 4x100m medley and 4x100m mixed medley this week as he seeks to add to his six Olympic medals. He was part of the British team that won gold in the 4x100m mixed medley and silver in the 4x100 medley in Tokyo.

Peaty took a break from swimming last year to address his mental health —battling with depression, alcoholism, and burnout that threatened his career. 

In Paris, he was bidding to join the legendary Michael Phelps and become the second swimmer to win three consecutive Olympic golds in the same event. Despite missing out by the narrowest of margins to share silver with USA’s Nic Fink, Peaty told Eurosport he was delighted with the outcome.

"True joy in every stroke. True joy, no matter what that scoreboard says," he said after the race.

The 4x100m medley relay heats begin on 2 August at 11:57 CEST.