TWO more wild swans found dead on a reserve in Dorset have tested positive for the deadly H5N1 bird flu, the Department for Environment, Food and Rural Affairs (Defra) said.

The latest results bring the total number of swans found to have the disease at the Abbotsbury Swannery, an open reserve in the Chesil Beach area, to nine.

Defra said further cases in the coming weeks "would not be unexpected", but there is still no evidence of widespread infection among mute swans or that it has spread to poultry.

However Defra has urged poultry keepers to remain vigilant for signs of bird flu in their flocks.

Earlier this week an epidemiology report into the case said H5N1 was most likely to have been introduced by an infected migratory bird.

It also said the strain of the virus is similar to those found in Europe in the latter part of last year.

The first birds to test positive were found dead at the open reserve in December during routine surveillance, while further swans were found to have the disease last month.

Restrictions on the movement of poultry and other captive birds in the Wild Bird Monitoring Area around Abbotsbury Swannery were imposed in the wake of the first positive tests, but were lifted last week.

However, movement restrictions in the Wild Bird Control Area remain in place, according to a Defra spokeswoman, and the control measures will be kept under review.

Enhanced surveillance, including patrols looking for dead birds, will continue in the area, Defra said.