Investigations are continuing into the source of an outbreak of bird flu on a commercial chicken farm in Mid Suffolk where thousands of birds are being culled.

After visits to all poultry premises in the area - where no further signs of the contagion were found - inspectors are continuing to probe the cause of a "low pathogenic" strain of avian influenza - or bird flu - at Homefield Farm in Athelington, near Eye, which was discovered on Tuesday, December 10.

The culling and disposal of around 28,000 broiler chickens - which are bred for meat rather than egg production - is "progressing well" and expected to be completed shortly, a Department for Environment, Food and Rural Affairs (DEFRA) spokeswoman said.

MORE - Bird flu outbreak is a 'wake-up call' for poultry farmersMeanwhile, a 1km restriction zone remains in place around the affected farm to limit the risk of the disease spreading.

A ban on movement of poultry remains in place on the farms within the zone, with no birds allowed to leave the premises without a licence.

But the spokewoman added: "Visits have taken place to all poultry premises in the area and we have not identified any reasons to suspect bird flu at any of these premises.

"A thorough investigation is in progress to determine the most likely source of this outbreak and any risk of onward spread.

"Culling and disposal is progressing well and we expect to complete this shortly."

After the cull is completed, Animal and Plant Health Agency (APHA) staff are set to carry out initial cleansing and disinfection of the premises.

This means the restriction zone will remain in place for at least 21 days following the initial disinfection at the infected premises, and while APHA officials complete their surveillance to ensure there are no signs of bird flu in the zone.

"Farms with good biosecurity are at a low risk of incursion of bird flu. We advise everyone with poultry to check our most recent biosecurity advice available on gov.uk," she said.

"Bird keepers should remain alert for any signs of disease, report suspected disease immediately and ensure they are maintaining good bio-security on their premises."

? Bird flu is a notifiable animal disease. If type of bird flu is suspected in poultry, keepers must report it immediately by calling the Defra Rural Services Helpline on 03000 200 301.

? If the public find dead wild waterfowl (swans, geese or ducks) or other dead wild birds such as gulls or birds of prey, they should report them to the DEFRA helpline on 03459 33 55 77.