|The World Health Organization (WHO) has declared a global flu pandemic after holding an emergency meeting, according to reports.
It means the swine flu virus is spreading in at least two regions of the world with rising cases being seen in the UK, Australia, Japan and Chile.
The move does not necessarily mean the virus is causing more severe illness or more deaths.
The swine flu (H1N1) virus first emerged in Mexico in April.
It has since spread to 74 countries.
Official reports say there have been 28,000 cases globally and 141 deaths and figures are rising daily
It is the first flu pandemic in 40 years – the last in 1968 with Hong Kong flu killed about one million people.
The current pandemic seems to be moderate and causing mild illness in most people.
One factor which may have prompted the move to a level six pandemic was that in the southern hemisphere, the virus seems to be crowding out normal seasonal influenza.
It is thought the move was not prompted by the situation in any one country but the reports of several pockets of community spread.
There have been almost 800 cases in the UK with some areas of Scotland being particularly hard hit.
The government has been stockpiling antivirals such as Tamiflu and has ordered vaccine, some doses of which could be available by October.
Chief medical officer, Sir Liam Donaldson said the WHO declaration of a pandemic would not significantly change the way the UK was dealing with swine flu at the moment.
But he added there could be some minor changes to who received antivirals.
“The declaration of a pandemic per se doesn’t make a big difference to the to the way we are handling the outbreaks we have.
“We are going to continue to investigate every case that occurs and treat their contacts with antivirals even though they may not be ill.
“The difference is that the Health Protection Agency has learnt a lot about approaching this question of antiviral prophylaxis and they are going to be treating the closer contacts of the cases, rather than the more far-flung contacts, because they feel that that is supported by what they know so far about how the disease is transmitting.
He added: “These flu viruses can change their pattern of attack, so when we come into the flu season in the autumn and winter in this country, when we expect a big surge of cases, we need to watch very carefully to see if the character of the virus is changing.”
Scottish health secretary Nicola Sturgeon said a move to level six means that countries need to be ready to implement pandemic plans immediately but the UK was already operating at a “heightened state of readiness”.
But it could affect the speed at which the UK gets pandemic vaccine supplies but that had been factored into pandemic planning.
Flu expert Professor John Oxford, said people should not panic as the outbreak was milder than others seen in the past century.
“It is global and fulfilling the requirements of a pandemic but I don’t think anyone should worry because nothing drastic has happened between yesterday and today.”
WHO ‘declares swine flu pandemic’