Sharon van Rouwendaal, of the Netherlands, took gold on a day of controversy at the open water women’s 10 kilometre marathon swimming event, with French swimmer Aurelie Muller disqualified for unsportsmanlike conduct after finishing second.

Muller, the world champion in 2015, looked like she had snatched silver just ahead of Italy’s Rachele Bruni, but was disqualified on review after she was adjudged to have pushed her opponent’s arm to stop her touching the board at the finish.

Bruni was promoted to the silver medal position and Poliana Okimoto was awarded bronze, making her the first Brazilian to win a medal in the sport.

“We were side by side, then when we were coming close to the touch she went over me, pushed me down with her arm on my shoulder and so I wasn’t able to touch the finishing board,” Bruni said after the race.

“Yes, the disqualification was justified because it’s not in the rules that she should be able to do that.”

Rouwendaal, who clocked a time of 1 hour 56 minutes and 32.1 seconds at Fort Copacabana, came in 17 seconds ahead of her nearest rival and said she had surprised herself by her margin of victory.

“If you would have asked me before the race, I would have never dreamed I would win by 17 seconds,” the 22-year-old added.

“The last 400 metres I knew I was going to win because I was watching. I couldn’t swim without watching. And the last 100 felt so amazing.”