The first case of swine flu has been confirmed in Ireland according to the Chief Medical Officer at the Department of Health, Dr Tony Holohan.
The man who had been tested had been living in the east of the country and had recently returned home from Mexico.
He is said to be recovering well.
The case was originally reported last Thursday.
Dr Tony Holohan said specimens tested in a laboratory in the UK proved positive this evening.
He also confirmed that there were no other probable or confirmed cases of the virus in Ireland.
Earlier, Professor Bill Hall, chair of the National Pandemic Influenza Group, told a news conference at Government Buildings that the virus reference laboratory has not been able to definitively confirm infection in the probable case.
The reason for this was a small amount of virus in the specimen.
He said the confirmatory tests were not sufficiently sensitive to detect the small amounts of virus
Prof Hall said they had not received results from the UK because they are also having similar sensitivities.
He also said all the indications are that despite severe cases in the US and Mexico, influenza is a relatively mild disease.
Hopes pandemic can be avoided
A senior official with the World Health Organisation has said there has not yet been a sustained spread swine flu outside North America, as would be required before the global pandemic alert level was increased again.
Dr Michael Ryan, the organisation's Director of Global Alert and Response, said the alert level is still at five on a six-stage scale.
Speaking during a news briefing at the UN agency's Geneva headquarters, he said he expected that a pandemic was imminent, but hoped it could be avoided.
However, health officials have warned that it is too early to ease vigilance against the swine flu virus.
The World Health Organisations has said that there were more than 600 confirmed cases of the virus worldwide.
18 countries confirm cases
At least 18 countries worldwide have now confirmed cases of swine flu, officially known as influenza A (H1N1).
The latest are Costa Rica, Italy, France, Denmark and Hong Kong.
In the US, where more than 140 cases have been reported, President Obama said they are taking the threat of this virus very seriously.
China has suspended flights to Mexico after Hong Kong authorities confirmed that a Mexican man who had travelled from Mexico via Shanghai had swine flu.
About 300 people have been placed under quarantine at the Hong Kong hotel where the 25-year-old man tested positive for the virus.
Meanwhile, the UK joined Canada, Spain, Germany and the US in reporting person-to-person transmission of the virus.
Mexico revises death toll downwards
In Mexico, the country where the outbreak began, the Health Minister said the spread of the flu is slowing and that the number of people being admitted to hospital had fallen.
The Mexican Government has reduced its estimate of the suspected deaths from the flu from 176 to 101.
It comes amid indications that the virus is not as dangerous as had been feared.
Elsewhere, the Egyptian authorities have begun
slaughtering its entire stock of 250,000 pigs as a precaution against the virus.
The move has been widely criticised as the World Health organisation says there's no evidence that pigs are transmitting the virus to humans.
Experts also point out that the flu cannot be caught from eating pig meat.