A fourth case of bird flu in Ireland has been confirmed by the Department of Agriculture.

The latest case occurred in a whooper swan found on the Longford-Leitrim border.

It is the second swan that has been found to be infected with the h5n8 flu virus.

A dead swan found in Tipperary last week was also confirmed to have the virus.

The other two cases occurred in a species of duck known as wigeons.

Last month, the Department of Agriculture activated regulations requiring all poultry and captive birds to be kept within a secure building amid concerns over bird flu.

As a result, all birds at Dublin Zoo were moved indoors for the foreseeable future due to the threat.

Nearly 150 ostriches, penguins, flamingos and other birds have been moved to a "back house" zoo facility.

The public is being advised not to handle dead or sick birds.

No outbreaks have been detected in poultry in Ireland so far.