Zanardi, who won two gold medals in Para-cycling at both London 2012 and Rio 2016, had been moved to a specialist recovery centre for head injuries last Tuesday (July 21).

His condition has worsened since, with doctors confirming he had been transferred back to intensive care due to "unstable clinical conditions".

The 53-year-old Italian will continue his treatment at Milan's San Raffaele Hospital.

Zanardi was placed in a medically induced coma and has had three operations since the horrific accident while competing in a national handcycling race in Siena in Italy.

No further information has been released about Zanardi's condition, and no timeframe has been given for his recovery.

The Italian competed in Formula One and sportscar racing during the 1990s.

In 2001, while competing in cart racing, he suffered a life-changing accident in which he lost both his legs.

Following his accident, Zanardi was fitted with two prosthetic limbs and after competing at the World Touring Car Championship turned to Para-cycling.

Tributes to Zanardi have been paid by Pope Francis and the Ferrari team, among others, since the accident.