An emergency committee of the World Health Organization (WHO) has not come to a final conclusion on whether to raise the current pandemic alert level, a spokesman said on Monday.

It's "not guaranteed" that the committee will decide to uplift the alert level, Gregory Hartl told a teleconference for the media, as experts in the committee continue their meeting at the WHO headquarters in Geneva.

The WHO's pandemic alert level currently stays at Phase 3, which means "no or very limited human-to-human transmission."

Hartl hinted that a raise to Phase 4 or Phase 5 are both possible, although no final decision has been made.

A rise to Phase 4 will mean the virus can cause "community-level outbreaks," indicating a significant increase in the pandemic risk, while Phase 5 means a pandemic is imminent.

The emergency committee was originally scheduled to meet on Tuesday, but given the severe situation of swine flu spread in Mexico, the United States and other countries, the meeting was brought forward to Monday.

The fact that the meeting was called earlier showed that the situation needs to be addressed urgently, Hartl said.