U.S. Air Force arms sales to international buyers doubled over the past two years and further increases are likely, a senior Air Force official said at the Paris air show on Monday.

Heidi Grant, deputy undersecretary of the Air Force for international affairs, told Reuters she expected further increases in coming years but it was difficult to project the exact level.

Grant said mounting pressure on the U.S. defense budget made it more important for U.S. allies to increase their ability to carry out intelligence, surveillance and reconnaissance missions, as well as aerial refueling.

The Air Force currently oversees 2,800 foreign military sales cases valued at $138 billion in 100 countries, Grant said.

"I see the caseload and the dollars continuing to increase," she said.

(Reporting by Andrea Shalal-Esa; Editing by Anthony Barker)