Free-range poultry and back-yard chicken flocks will be forced indoors from Monday in a bid to prevent the spread of bird flu.

Chief vets announced the mandatory housing measures will begin on November 29 to protect commercial poultry and captive birds from avian influenza - the virus which prompted culls of thousands of turkeys and ducks in East Anglia last winter.

It follows a rising number of confirmed cases in commercial and domestic pet flocks across the country - including one at a residential property on the Holkham estate on Sunday.

From Monday, it will be a legal requirement for all bird keepers across the UK - whether large commercial farms or back-yard hobbyists - to keep their birds indoors and follow strict biosecurity measures.

Free-range farmer Mark Gorton is a director of Traditional Norfolk Poultry, based in Shropham near Attleborough, and also a member of the national poultry board.

"I think it is a sensible thing to do," he said. "We are shocked at how many cases there have been and how quickly it has spread.

"We have got to do what we can to stop this disease spreading any more.

"We are well-practised at this and we have got plenty of space to house our free-range birds.

"But there will be challenges because they are used to running around the woods and the fields so it will be a big change for them and we have to be really careful how we manage them, and to give them extra enrichment inside the houses. At the end of the day it is for their benefit."

Mr Gorton also urged domestic keepers of pet flocks to play their part in protecting East Anglia's valuable poultry industry.

"People need to realise the implications for the rest of the poultry industry, which employs thousands of people, from the risks associated with someone with a few chickens in their back yard," he said.

"It affects all of us, so they need to act responsibly for their own benefit, for our benefit, and to keep their birds safe as well."

UK food and health agencies advise that the risk to public health from the virus is very low and that avian influenzas pose a very low food safety risk for consumers.

For biosecurity advice and information on preparing for the mandatory housing measures, see Defra's avian influenza web pages.