A 99-year-old war veteran has become a celebrity by raising at least 8.5 million pounds ($10.7 million) for Britain's health service with a walk around his garden in the coronavirus crisis.

Retired army captain Tom Moore, who has used a walking frame to move around since breaking his hip, has set himself the target of walking the 25 metres around his garden 100 times before his 100th birthday later this month.

The story has lifted the hearts of a nation stuck in lockdown for the last month and weary of the relentless wave of grim news. So far, nearly 13,000 people with COVID-19 have died in British hospitals, the fifth-highest total globally.

Moore's initially modest aims have been blown away as media attention from around the globe has zoomed in on his garden in Bedfordshire, central England.

"It was a joke (originally)," he told Reuters. "But then it seemed to get bigger and bigger, until now. I mean we now seem to have got into the millions, which is rather a lot.

"I never even dreamt of that sort of money. It's the National Health Service, who are doing such a magnificent job for us all."

Now Moore has a target of 10 million pounds in his sights.

"So long as I can go on walking, so long as people are giving money towards it, I'll keep on walking," he said.

His son-in-law Colin Ingram said Moore wanted to give something back after receiving such good care from the state-run health service when he broke his hip two years ago and in subsequent hospital visits.

"It was literally just something we were doing in the garden to keep him walking on his recovery from his hip operation," Ingram told Reuters.

"We said we'd give him a pound a lap, and thank goodness I didn't say I'd match any money he raised!"

Moore, pictured with his campaign medals from his time as an army officer in Asia in World War Two, has featured on UK news programmes and front pages, and his family are fielding interest from as far afield as the United States, France and Australia.

Raising money for the health service has given Moore a new lease of life, said his son-in-law.

"He's coming down in the morning sprightly and loving it. If the public wants to keep on donating then he'll keep on walking," Ingram said.