Global demand for air travel rose 4.6 percent in May, slowing from a strong start to the year, with attacks in major cities and the fragile global economy affecting travel demand, the International Air Transport Association (IATA) said on Thursday.

Capacity measured in available seat kilometers rose 5.5 percent, meaning that load factor - a measure of how full planes are - dropped 0.7 percentage points to 78.7 percent, IATA said in its monthly traffic update.

"The shocks of Istanbul and the economic fallout of the Brexit vote make it difficult to see an early uptick", added IATA Director General Tony Tyler.

The airport association ACI Europe said earlier on Thursday that Britain's vote to leave the European Union was not expected to impact overall European air traffic levels this summer but could knock demand for air transport later this year.[nL8N19T1ZT]

(Reporting by Sylwia Lasek; Editing by Vicoria Bryan)