ISTANBUL, June 5 (Reuters) - Saudi Arabia's new airline Riyadh Air is in talks with planemakers Airbus and Boeing to buy a significant number of narrow-body jets - part of what may become a trio of inaugural orders, Chief Executive Tony Douglas said.

The creation of a second Saudi national airline, with industry veteran Douglas as its CEO, was announced alongside an order for up to 72 Boeing 787s in March, as the kingdom moves to diversify its economy and serve over 100 destinations by 2030.

Interviewed on the sidelines of a global airlines meeting in Istanbul, Douglas declined to give the size of the planned second order for narrowbody jets, but told Reuters: "It's not going to be insignificant by any stretch of the imagination."

He added: "That might not be our last order either". (Reporting by Tim Hepher; Editing by Susan Fenton)