Three new states reported infections - Hawaii, Washington and Oklahoma - showing that the infection had spread to 41 US states.
The centre said it "expects that more cases, more hospitalisations and more deaths from this outbreak will occur over the coming days and weeks".
In other developments:
The UK reported another four confirmed cases, up to 32. The new cases were all associated with travel to Mexico
France's tally rose from five to seven confirmed cases
Poland announces its first confirmed case, in a woman recently returned from the US
The US Navy postponed an aid mission to the South Pacific after a sailor on the vessel scheduled to take the trip developed swine flu. Nearly 50 other sailors on the California-based USS Dubuque also showed symptoms of the new H1N1 virus
A woman in Texas became the first US resident believed to have died from swine flu. She had other health issues, officials said
When the flight from China touched down at Mexico City's International airport carrying those kept in quarantine, First Lady Margarita Zavala greeted the 136 passengers.
Seventy-two had been in Shanghai, 18 in Beijing, 34 in Guangzhou and 12 in Hong Kong. None had flu symptoms, Mexican diplomats said, according to AP news agency.
The World Health Organization (WHO) urged nations to remain vigilant in spite of the apparently relatively mild nature of swine flu, saying a global pandemic remains a threat.
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