'Swine flu' kills 60 in Mexico
The virus is normally linked to contact with pigs
The World Health Organisation says it suspects swine flu has killed 60 people and infected 800 others in Mexico.
A WHO spokeswoman said the majority of the cases were in the capital, Mexico City, and a small number in central areas of the country.
Seven non-fatal cases of a new form of swine flu have also been confirmed in the southern United States.
Experts will carry out tests to determine whether the viruses behind the outbreaks are linked.
The WHO has opened its strategic health operations centre, which operates during periods of acute public health risks.
'Flu-like illness'
WHO spokeswoman Fadela Chaib said "unusual end-of-season influenza activity" was noticed in Mexico starting from the end of March.
"To date there have been some 800 suspected cases with flu-like illness, with 57 deaths in the Mexico City area," she said.
Three more deaths and 24 suspected cases were also recorded in San Luis Potosi in central Mexico, she said.
"We're dealing with a new flu virus that constitutes a respiratory epidemic that so far is controllable," Mexican Health Minister Jose Angel Cordova said on Thursday.
The Mexican authorities are currently conducting tests to determine what the virus is. Schools have been closed in affected areas and people urged to avoid large crowds, shaking hands and kissing.
In the US, experts are investigating a new form of swine flu that they say combines pig, bird and human viruses, after seven people fell ill in Texas and California.
"This is the first time that we've seen an avian strain, two swine strains and a human strain," Dave Daigle, a spokesman for the US Center for Disease Control and Prevention (CDC), told AFP.
The CDC said none of the seven victims had been in contact with pigs, which is how people usually catch swine flu.
It was tracking those who had been in contact with the seven to see if they had fallen ill, it said.
BBC NEWS | Americas | 'Swine flu' kills 60 in Mexico