International Air Transport Association data showed passenger traffic rose 6.8 percent in May from a year ago.
Air freight -- an important measure of world trade -- fell 4 percent, IATA said. But freight volumes rose 1.2 percent on April, which, IATA said, would help alleviate pressure on airline profit from continued high fuel prices.
"There are risks associated with political unrest in the Middle East and the European currency crisis," IATA director general and chief operating officer Giovanni Bisignani said.
Political unrest in Egypt and Tunisia has had a dramatic impact, with flights to the two destinations down about 20 percent, according to IATA.
European carriers saw air traffic expand 10.9 percent, boosted by increased economic activity in northern Europe and a weaker euro encouraging trade and inbound travel, it said.
Passenger traffic in Asia grew 4.7 percent in May, well below the global average, due to continuing weakness in Japan's market following the earthquake, tsunami and nuclear crisis, it said.
"We still expect the industry to make $4 billion this year. That is a pathetic 0.7 percent margin and another shock could alter the industry's fortunes dramatically. It is another tough year for a very fragile industry," Bisignani said.
The IATA has forecast 8 percent annual growth in revenue this year to about $600 billion. Air cargo revenue was seen increasing 9 percent to $72 billion.
International air travel in first and business class has slumped because of Japan's nuclear crisis, weakening world trade and Middle East turmoil, IATA said last week in a monthly report on premium travel in April.
The Geneva-based body represents carriers accounting for 93 percent of international flights. (Reuters)
