UP to 12,000 chickens could have to be killed after bird flu was found at a farm near the Powys border.

The Department for Environment, Food and Rural Affairs (DEFRA) said all birds at a site six miles from Presteigne where the flu had been found would be humanely culled.

The Government department gave a map reference where the three-kilometre protection zone and 10-kilometre surveillance zone centre around.

And that site is Corbett Farms' Ox House Farm off Ledicot Lane, Shobdon which is in the Avara supply chain. According to Herefordshire Council planning documents, it houses 12,000 birds.

The two zones, which extend as far as 10-kilometres radius of the site, are to prevent the flu from spreading.

The 10-kilometre control zones mean 314.2 square kilometers of Herefordshire, as well as across the border into Powys, must follow certain rules surrounding poultry.

In a statement, Corbett Farms confirmed the flu had been found at its Ox House Farm site, but there were no cases at its other sites.

But it said a public footpath running through the site is closed as access is restricted to control the disease.

The strain of avian flu found at all 25 sites in England so far, including the site near Leominster, is H5N1.

The NHS said the strain does not infect people easily and is not usually spread from human to human.

But several people have been infected around the world, leading to a number of deaths, it said.

An Avara spokesperson said: “We can confirm that a farm within the Avara supply chain has had Avian Influenza confirmed on site.

"We’re working closely with APHA (Animal and Plant Health Agency) and Defra (Department for Environment, Food and Rural Affairs) to manage the incident, and want to emphasise that there are no concerns about consequences for human health.

"Any outbreak causes inevitable disruption and there are a number of other farms in the area, but we’re already revising our plans and are confident that we can manage the impact and continue to meet our commitments.

"We do not comment on bird numbers by farm.”

In a planning application submitted to Herefordshire Council to redevelop one of its other sites, Corbett Farms said 12,000 birds were kept at Ox House.

Consultants explained in a design and access statement for the Uphampton site that all of the Avara broiler sites in north Herefordshire are supplied chicks from the hatchery at Shobdon, next to the church.

The eggs for these chicks are only supplied by eight Avara-owned sites and Corbett Farms sites.

Consultants said Corbett Farms has three rearing sites that take day-old chicks and then these go to one of the eight sites at the point of lay.

"The output from the hatchery has continually increased in recent years, and if the economy around Avara is to be maintained, there is a need for Corbett Farms Limited to continue/grow their part of the rearing laying process," the statement said.

"This proposal is for the redevelopment of an existing site to bring it up to latest standards.

This site, being only 2km by road (400mm straight line), is the closest site to the hatchery and so has the lowest environmental impact for egg deliveries."

If plans are approved, the Ledicot Lane site, which houses 12,000 birds, would be shut down.

Public health advice remains that the risk to human health from the virus is very low and food standards bodies advise that avian influenzas pose a very low food safety risk for UK consumers.

But people are told not to touch or pick up any dead or sick birds that they find and instead report them by calling 03000 200 301.

"There is no impact on the consumption of properly cooked poultry products including eggs," DEFRA said.

The two zones have rules which will affect the movement of birds and eggs, the removal of litter, manure and slurry, and other biosecurity measures.

The measures came into force at 9pm on Thursday after being approved by the Secretary of State at 8.45pm.