Six dead swans found in Down and Antrim did not die from any strain of bird flu. The announcement was made just before 6pm yesterday, following a preliminary assessment of the carcasses.
Scientists at the non-governmental Agri-Food Biosciences Institute laboratory at Newforge in south Belfast passed their findings on to the Department of Agriculture and Rural Development (Dard).
Chief veterinary officer Bert Houston said: "So far this year Dard has tested 23 swans, all of which have been negative for highly pathogenic avian influenza.
"We will continue to undertake such testing as necessary," he added.
He appealed for any member of the public who finds a dead swan, or three or more dead wild or garden birds in the same place, to report the finding to Dard. "We will provide advice on what action to take and will arrange to have the birds examined if we consider this to be appropriate.
"If the dead bird is a single small garden or wild bird, then you do not need to call the department," he added.
"Instead you should place the bird in a plastic bag, dispose of it in your rubbish bin and, as a precaution, thoroughly wash and clean your hands."
The department, under minister Lord Jeff Rooker, has insisted Northern Ireland is ready to counter any outbreak of the highly contagious strain of avian influenza known as H5N1 following the confirmation of a case in the Fife region of eastern Scotland on Thursday.
Mr Houston said there was a contingency plan in the event of bird flu being diagnosed.
"It will involve us setting up a series of command structures, getting a local exotic disease centre placed on the ground. We will put in 3km protection zones, 10km surveillance zones and apply all the control measures required by the European Commission," he said.
Other British officials moved to allay public fears about the H5N1 strain of bird flu.
"I don't think that one dead swan is a crisis," government chief science adviser David King told the BBC yesterday.
"There is a better chance of a person winning the national lottery than catching bird flu in the UK today," said Jim Robertson, a virologist from the National Institute for Biological Standards and Control.