(Reuters) - Global demand for air travel rose 5.9 percent in July, the first month of the peak summer travel period, thanks to the low price of oil helping to keep fares low and thus boosting demand, the International Air Transport Association (IATA) said.

But European carriers saw the slowest growth in demand, of 4.1 percent in July, IATA said in its monthly traffic update on Wednesday, after attacks deterred tourists, especially from Asia and the United States.

"Long-haul travel to Europe, for example, suffered in the aftermath of a spate of terrorist attacks. And the mature domestic markets are seeing demand growth stall while Brazil and Russia contract," IATA head Alexandre de Juniac said in a statement.

IATA added that typically the impact of terror-related attacks is just temporary, but that the repeated nature of recent events suggests the impact may be longer-lasting this time.

Globally, capacity measured in available seat kilometers rose 6.0 percent, faster than demand, and meaning that load factor - a measure of how full planes are - dropped 0.1 percentage point to 83.7 percent.

(Reporting by Daria Kowalewska; Editing by Victoria Bryan)