"Health systems need to be able to prevent, detect, treat and mitigate cases of illness associated with the virus."

WHO has urged calm following its decision to declare a pandemic, and has pointed out that in some instances recovery from mild cases of the virus is possible without medication.

The latest global tally for H1N1 from the organisation showed 29,669 cases, with 145 deaths, although most cases have been mild and required no treatment.

Travel bans

Margaret Chan, the WHO's director general, said on Friday that her agency would work with the World Trade Organisation and others to ensure nations do not impose travel and trade bans over the H1N1 virus.

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The agency has advised against countries implementing travel restrictions such as border closures and the restriction of movement of people, goods and services to contain the virus.

Morocco is the latest country to confirm its first case of H1N1 after an 18-year-old woman returned home from studying at a university in Canada, the country's health ministry said.

The woman arrived on Wednesday at her home city of Fez on board a Royal Air Maroc flight via Casablanca from Montreal and showed the first symptoms, the ministry said in a statement on Friday.

"Results of [laboratory exams of a sample] have confirmed the existence of AH1N1 virus on the young woman, whose state of health is currently stable," the statement said.

Authorities were providing the required health care to the woman's family and checking whether any of the passengers who were on the flights Montreal-Casablanca and Casablanca-Fes might be infected by the virus.

In a statement, Hassan II Hospital in Fes, where the woman was being treated, said: "The woman, who is being treated over a five-day period, has shown signs of improvement in her health, namely her fever has dropped."

Vaccine trials

Novartis, the Swiss drugs company, has said that it expects a vaccine for the H1N1 virus to be available by the autumn after it produced the first batch for testing ahead of schedule.

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WHO declares H1N1 flu pandemic

The vaccine will enter clinical trials next month.

Novartis, Sanofi-Aventis, GlaxoSmithKline and Solvay have all obtained the H1N1 seed virus in recent weeks and aim to have a vaccine ready ahead of the northern hemisphere flu season.

WHO has estimated vaccine makers could produce up to 4.9bn pandemic flu shots a year in a best-case scenario, leaving some of the world's 6.5 billion population unprotected, particularly if more than one injection was needed to gain immunity.

Chan has said that different regulatory authorities need to work together to speed registration of a safe vaccine.