A Yate man whose family claim thousands in benefits has been caught racing round a bumpy motocross track despite drawing public cash for having a bad back.

Gary Bateman has 11 children with partner Joanne Sheppard and the couple are claiming £30,000 a year in tax-free benefits, tax credits and housing allowances.

But last weekend the 45- year-old, who has not worked for years, was pictured taking part in a gruelling six-hour motocross training event in Chippenham, Wiltshire.

Mr Bateman says he has not been able to work following an operation in November 2005, but mentions the hobby on his MySpace page.

The couple live in a three-bed council house in Yate, with nine of their 11 children, aged nine months to 14 years and the Department of Work and Pensions says it will now be investigating the claims.

But Mr Bateman said: "I've got nothing to hide. I've got to keep myself occupied. I'm not lazy. It's not as if I'm on my bike day in and day out and I don't go over big jumps. Just because I can ride my bike doesn't mean I can work. I'd love a job but I've a bad back."

Mr Bateman could not recall how long it was since he had a job but said his back trouble began about 1999.

His partner has not worked since getting pregnant at 17 and has children by three different men.

Asked about Mr Bateman's biking, she claimed he "doesn't ride, he just watches", until told there was film of him racing around the track.

The couple made news in 2006 when they boasted of planning a £1,500 Christmas spending spree on taxpayers' money. Mr Bateman said at the time the family bought so many gifts that the pile looked like Mount Everest.

Ms Sheppard added: "Last year the kids had so many presents you couldn't even get in the front room. They got so bored opening them all they started chucking them across the room."

Mr Bateman said: "It's like Mount Everest in here with the presents at Christmas. Last year we needed 15 bin liners just for the wrapping paper and packaging.

"It's not Santa's grotto; more like Santa's mansion."

Ms Sheppard, at the time, added: "I understand people who criticise. But I can't go out to work because my kids are my job and I don't like the idea of leaving them with a childminder. And Gary can't go out to work because he is on the sick after a back operation. This may look like the life of Riley but it's not. We don't get a lot of benefits."

It has also been reported the couple's children get private ballet lessons and gymnastics classes, regular days out at a local play centre and annual trips to a holiday camp.

In July 2003 Bateman was hailed a hero after delivering his daughter Brogan, at home with help over the phone from paramedics who arrived after the birth.

The Department of Work and Pensions said: "We take allegations seriously and investigate."