Demand for global air freight, measured in freight tonne kilometers, rose only 0.9 percent in May on broad weakness in world trade volumes, the International Air Transport Association (IATA) said on Wednesday.

"Global trade has basically moved sideways since the end of 2014 taking air cargo with it. Hopes for a stronger 2016 are fading as economic and political uncertainty increases", IATA Director General Tony Tyler said in a statement.

Available capacity rose 4.9 percent in the month, meaning that load factors fell by 1.7 percentage points to 41.9 percent.

The overcapacity means air cargo companies are battling falling yields, with Lufthansa Cargo describing the drop in prices as a "landslide".

(Reporting by Daria Kowalewska; Editing by Victoria Bryan)