In a post on Instagram, Pellegrini said she began experiencing symptoms on Wednesday (October 14) and tested positive for coronavirus yesterday. 

The 32-year-old was set to leave her training camp in Verona to captain the ISL team Aqua Centurions in Budapest, but has now withdrawn from the competition. 

"I'm so sorry, I couldn't wait to restart a normal season," she said.

"I do not know whether to laugh or cry, in truth I have cried until now."

Pellegrini is the world champion and world record holder in the 200 metres freestyle, having claimed Olympic gold in the distance at Beijing 2008.

She also claimed silver in the 200m freestyle at Athens 2004 and is targeting her fifth Olympic Games at Tokyo 2020 next year. 

Training partner Stefania Pirozzi, Dutch swimmer Femke Heemskerk and Hungarian world record holder Kristof Milak have also tested positive for COVID-19 in the run-up to the second season of the ISL, which gets underway in the Hungarian capital today. 

Ten teams are competing in total, with participants entering a COVID-19-secure bubble upon arrival. 

All swimmers, coaches and entourages were tested before entering the bubble. 

Anyone who tests positive will have to quarantine and follow strict rules for self-isolation. 

Competition is scheduled to take place over a five-week period and finish on November 22.