Former Formula One driver Alex Zanardi is in a serious condition in hospital in Italy following an accident during a handbike relay.

The 53-year-old suffered a severe head injury in a crash with a lorry, according to reports in Italy.

The Santa Maria alle Scotte hospital in Siena said he was transported by helicopter from Pienza and underwent emergency neurosurgery before being moved to intensive care.

The hospital added Zanardi, who had both legs amputated following a crash in 2001, remains in a "very serious" condition.

The Italian is a four-time Paralympic champion hand cyclist who was taking part in the Obiettivo Tricolore event, which sees participants journey across Italy on handbikes, wheelchairs or cycles. 

A host of prominent figures from the racing world and beyond have taken to social media to send Zanardi their well-wishes.

Former Formula One world champion Mario Andretti tweeted: "I am so anxious and frightened about Alex Zanardi that I'm holding my breath. I am his fan. I am his friend.

"Please do what I'm doing and pray pray for for this wonderful man."

Williams Racing said: "The thoughts of our whole team are with former driver Alex Zanardi after he was injured in a hand bike accident earlier today.

"Alex is one of life's truly inspiration(al) people and as we all know, a fighter through and through. Stay strong and Forza Alex".

Meanwhile Italian prime minister Giuseppe Conte said Zanardi had the support of the entire country.

"You have never given up and with your extraordinary fortitude you have overcome a thousand difficulties," he tweeted.

"Come on Alex Zanardi, don't give up. All of Italy is fighting with you."