Cheryl has broken her social media silence to voice support for Billy Monger as he tackles a 140-mile triathlon-inspired challenge for Comic Relief.

The former Girls Aloud star, 37, met with the racing driver, who lost both of his legs in a racing accident three years ago, on Thursday during the latest stage of his journey.

The 21-year-old is attempting to tackle the distance on foot, by kayak and by bike to raise money for Red Nose Day, with different legs taking place around the country.

Cheryl shared a video on Instagram of herself in a car on her way to meet Monger.

She told her 3.5 million followers: “Today is the first day I’ve actually been somewhere to work and I went to meet up with Billy Monger.

“If you haven’t heard of him, you should really go and look him up.

“He is an incredible 21-year-old, who has been through a horrific accident. He lost both of his legs when he was 17 and got straight back up and at them, and did all the things he wanted to do. Mind over matter.”

Later, Monger took over her account and shared a video urging her followers to donate.

Billy Monger in the Lake District
Billy Monger in the Lake District (Comic Relief/PA)

Cheryl added: “I was telling Billy how generous and how supportive and kind you all are.

“So we thought we would use this opportunity to say Billy is at the end of his challenge, he is doing incredible, we need some support, so please donate.”

The pop star, who shares three-year-old son Bear with former One Direction star Liam Payne, last posted on the social media site in June, sharing a black square in support of the Blackout Tuesday initiative for racial equality.

Monger’s journey was disrupted on Tuesday when winds of 50mph and high waves prevented him from crossing a lake in the Lake District by kayak.

He began racing aged just six, but in April 2017 at a British F4 race he was left with life-changing injuries that resulted in the amputation of both his legs.

However, he was back at the wheel within a year and has now been training for months to take on the charity challenge.

People at home will be able to see all the highs and lows of Monger’s challenge in an hour-long special documentary, filmed by a reduced crew, on BBC One in March.