Seoul  - South Korean authorities were investigating a possible case of a swine-flu infection Tuesday.

An influenza infection was detected in a 51-year-old South Korean woman who returned from a trip to Mexico on the weekend, the Korean Centres for Disease Control and Prevention said.

The centre was testing whether the woman contracted the mutated H1N1 virus, the strain identified in the swine-flu outbreak in Mexico, which may have cost up to 149 lives so far. Test results are expected in one or two days, the centre said.

The woman was among three South Koreans who tested after displaying flu-like symptoms following their return from Mexico, but the other two have already tested negative for influenza. (dpa)