The Health Ministry said in a statement that the change in preparedness levels will not involve any serious operative changes, since the ministry had contingencies for such a situation.

On Monday, the World Health Organization (WHO) raised its global alert level from Phase 3 to Phase 4, signaling the swine flu virus was spreading from human to human in community outbreaks, but it did not declare a full-blown pandemic.

According to the WHO's program for dealing with possible influenza pandemics in such cases, Phase 3 deals with preparedness for only sporadic infection of humans by animals, whereas Phase 4 deals with readiness for virus spread caused by sustained human tohuman transmission.