Clarke Carlisle is 'alive and stable' but 'very poorly' after being hit by a lorry in North Yorkshire on Monday morning.

Carlisle, the former Leeds, Burnley and Queens Park Rangers defender, who went on to be chairman of the Professional Footballers' Association and in 2010 achieved acclaim for his appearance on TV quiz show Countdown, was airlifted to Leeds General Infirmary.

Carlisle's wife Gemma tweeted on Tuesday afternoon: 'Clarke's very poorly but he's alive and stable. Best Christmas gift we as a family could wish for. Thanks again.'

Clarke Carlisle poses for a photo while he was PFA chairman back in July 2013

Carlisle has been working as a commentator for ITV since retiring in May 2013

Carlisle celebrates while playing for Queens Park Rangers against Colchester in September 2002

A picture of the A64 road in North Yorkshire, near to where Carlisle was hit by a lorry on Monday

Carlisle was hit by a lorry near the North Yorkshire village of Bishopthorpe on Monday morning

The incident took place near Bishopthorpe at 7.30am on Monday, with the road closed to allow the air ambulance to arrive at the scene. Police are appealing for witnesses.

A North Yorkshire Police spokeswoman said: 'The collision involved a male pedestrian and a lorry.

'The injured man has been airlifted to Leeds General Infirmary with serious injuries.

'The road was closed to allow the air ambulance to land and to allow collision investigators to examine the scene.'

A PFA statement read: 'Everyone is keeping Clarke Carlisle in their prayers and thoughts.

'We visited Clarke at the hospital yesterday and we are offering our full help and support to him and his family at this difficult time.'

Carlisle, considered one of the most intelligent footballers of his generation with 10 Grade A GCSEs, made more than 500 appearances for nine clubs in a career that spanned 16 years and became the first player to appear on Countdown.

In 2002 he was awarded the title 'Britain's Brainiest Footballer' by BBC Sport and in 2011 he became the first footballer to appear on BBC's topical debate show Question Time. He was on the show again in 2012.

His last match was in May 2013 for Northampton Town, when they were beaten 3–0 by Bradford City in the League Two play-off final at Wembley. He quit football five days later.

Since retiring, he has been a regular pundit on ITV, working at the 2014 World Cup and on their Europa League coverage. He is a leading ambassador for anti-discrimination group Kick It Out. On Monday night they posted on Twitter: 'The thoughts and prayers of everyone here are with Clarke and his family. Stay strong our dear friend — keep on fighting.'

The defender celebrates winning promotion to the Premier League with Burnley in 2009

Carlisle has appeared several times on Channel 4 gameshow Countdown

The 35-year-old has also been a guest on BBC current affairs programme Question Time

Carlisle with former England and Liverpool midfielder John Barnes

The former central defender won Britain's Brainiest Footballer competition on ITV in 2002

Carlisle challenges Arsenal's Thierry Henry in 1999 while playing for Blackpool, his first club

In September 2013 he released his autobiography You don't know me, but ... a footballer's life, in which he wrote powerfully about a suicide attempt after a serious injury in his playing days.

Carlisle, who has three children, presented a BBC documentary called Football's Suicide Secrets and has been open about his own battles with depression.

The football community was quick to pledge its support to Clarke and wish him a speedy recovery.

Arsenal manager Arsene Wenger said: 'I would like to wish him well. It was an accident and hopefully he will recover very quickly but of course we wish him very well.'

The Football Association tweeted: 'The thoughts & prayers of all at The FA are with Clarke Carlisle & his family at this sad time.'

The Football League added: 'Our thoughts & those of everyone that watches Football League clubs will be with Clarke Carlisle and his family this evening.'

QPR midfielder Joey Barton and former Downing Street communications chief Alastair Campbell, a Burnley fan, took to Twitter to wish Carlisle well.

'Just heard the news about Clarke Carlisle. My thoughts are with his friends and family,' Barton wrote.

Campbell tweeted: 'Really hoping @clarkecarlisle going be ok. Thoughts with Gemma/two lovely kids. A great @BurnleyOfficial man and mental health campaigner.'