The H1N1 virus has killed more than 700 people worldwide since emerging in April, and countries could consider closing schools to slow its spread, the World Health Organisation has said.

It also said it was up to national health authorities to decide what measures they impose to slow the spread.

British researchers writing in the journal Lancet Infectious Diseases said that governments needed to draft plans for when and how to close schools.

A WHO spokeswoman said some 125,000 laboratory-confirmed cases have been reported worldwide as of yesterday.