A farm near Helsingborg with approximately 230,000 laying hens has been hit by the serious and contagious Newcastle disease, according to test results from the National Veterinary Institute (SVA).

Symptoms among the birds include reduced egg production and eggs without shells, reports the Swedish Board of Agriculture.

An access ban has been imposed on the affected farm, and neither animals nor animal products may leave the premises.

Infected hens will be culled, and contact tracing has started.

It is unclear if more farms are affected, says Maria Nöremark, deputy state epizootologist at SVA.