"In other words, the outcome of yesterday's referendum could reduce air passenger growth by 1.0-1.5 percentage points each year over the near term," the industry group said in an analysis. Air freight will be affected by lower international trade in the longer term, it said.

The regulatory impact on the aviation sector would depend on the nature of the exit terms and future arrangements between Britain and the European Union. "In effect the choice comes down to a trade-off between two key issues; access for UK airlines and customers to the European Single Aviation Market and policy freedom for the UK to set its own regulations," IATA added.

(Reporting by Stephanie Nebehay; Editing by Andrew Heavens)