International airlines were requested to review their emergency planning Sunday amid rising global concern about the spread of a deadly new strain of swine flu from Mexico.

The Geneva-based International Air Transport Association, or IATA, stopped short of requesting airlines take any additional steps, noting industry guidelines have been drawn up with the World Health Organization and airport and airline agencies.

No airlines have so far announced any plans to cancel flights to and from Mexico, though most active in the region revised their ticket policies, allowing passengers to reschedule travel for a later date at no extra charge.

"At the present time, IATA recommends that airlines review their preparedness plans for public health emergency and consider how they may be implemented in the event that the current situation becomes more widespread," said the trade body in a statement posted on its Web site Sunday. "No specific additional measures are currently advised. Recommendations will be reviewed in light of WHO evaluation of the evolving situation."

Delta Air Lines Inc. (DAL) and Air Canada issued advisories Sunday that allows passengers to and from Mexico City to change travel plans at no additional cost. "We are working directly with the Centers for Disease Control (CDC)," said Delta in an emailed statement. "At this time, there is no impact to our operation, but we are allowing customers to make a one-time to change travel plans to Mexico through May 4."

Canadian officials have identified six confirmed cases of swine fever among people who have recently returned from Mexico. Cases have also been identified in three U.S. states.

Other U.S. carriers including American Airlines, a unit of AMR Corp. (AMR), Continental Airlines Inc. (CAL), United Airlines, a unit of UAL Corp. (UAUA) and US Airways Group Inc. (LCC) revised their own ticket restrictions. No-fee changes can be made between May 4 and May 7, depending on the airline.

Airline passengers are viewed as the most likely means for the international transmission of viruses with pandemic potential, and the industry has honed its preparations in the wake of the Sars avian flu epidemic in 2003. Sars had a devastating impact on airline traffic to and from Asia and within the region, and the outbreak of swine flu comes as passenger numbers to central and South America have started to falter in the wake of the global economic slowdown.

-By Doug Cameron, Dow Jones Newswires; (312) 750 4135; doug.cameron@dowjones.com