The number of passengers on international routes has risen every month this year from unusually low levels in 2011 when political turmoil in Arab countries and an earthquake and tsunami in Japan disrupted travel.

Geneva-based IATA's director-general and chief executive Tony Tyler said the rise in passenger traffic was encouraging, adding that factors such as high fuel costs were still a worry for airlines.

"(Passenger growth) comes against an environment of continuing high oil prices and growing economic uncertainty. So translating the stronger demand into profits will be difficult," he said.

IATA airlines, which include major global carriers and most domestic operators but not low-cost airlines, account for 84 percent of world traffic.

There were signs the slump in cargo demand may have bottomed out, with the Middle Eastern airlines showing particularly strong growth, IATA said.

"It is possible to identify the start of a growth trend in cargo for some parts of the world. But economic uncertainty in Europe makes it very difficult to be optimistic in the near to medium-term," said Tyler.

(Reporting by Tom Miles and Emma Farge; Editing by Dan Lalor)

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