Mexico City - Mexican authorities corrected the number of people killed by swine flu from previously 20 to seven.

Miguel Angel Lezana, director of the national epidemiological and disease control centre, said late Tuesday the mutated H1N1 swine flu virus was confirmed to be responsible for seven deaths. The other 13 cases could not be confirmed yet.

Mexican authorities previously put the swine flu death toll at 20. Lezana said additional testing was conducted on recommendation of the the Geneva-based World Health Organization.

At least 159 people have been killed by flu infections in Mexico, Health Minister Jose angel Cordova said. More than 1,300 people were hospitalized out of a total of around
2,500 suspected cases, he added.