COPENHAGEN (Reuters) - Ducks and geese at a commercial hatchery on the island of Funen that were tested for avian flu had a less serious low-pathogenic strain of the virus, the Danish Veterinary and Food Administration said on Friday.

The farm, with around 20,000 ducklings and goslings, was cordoned off on Thursday while authorities tested the flock.

The restrictions still apply and the birds will be culled as a precaution because the less serious variety of the virus can develop into highly pathogenic H5, the administration said in a statement.

The infection was discovered through routine tests put in place by the Danish authorities earlier this year.

Three other commercial farms, which have supplied the afflicted farm with hatching eggs, have been placed under observation.

In May, Denmark halted exports of poultry from Funen after birds on a smallholding farm tested positive for the deadly H5N1 strain of avian flu.