The US military continues talks with potential foreign buyers of Bell Boeing's V-22 Osprey as the service works to decrease the tiltrotor's costs.

US Marine Corps Col Daniel Robinson, manager of the V-22 joint programme office, tells reporters that the service is getting closer to securing a contract to sell V-22s to Israel, and says the military has a team of negotiators in that country working on a deal.

He adds that up to one dozen other countries have shown significant interest in the aircraft, but declines to specify those nations or say how close the military and Bell Boeing are to securing an order.

"Its definitely growing in demand," he says.

Robinson's comments, made during a press briefing at the Navy League's Sea-Air-Space Exposition near Washington, DC, on 7 April, follow an announcement in January that Israel requested permission from the US Defense Department to buy six V-22s.

Then, in February, at the Heli-Expo, Bell Helicopter chief executive John Garrison said Israel is now interested in acquiring a total of 12 aircraft, six of which would come from existing orders that are assigned to the Marine Corps.

Any order from Israel or another country would help Bell Boeing preserve V-22 sales beyond 2015 and could help keep production alive past 2019.

Presidential MV-22 - Bell

Robinson notes, however, that the production line has enough capacity in the next few years to handle some new aircraft orders.

Meanwhile, Robinson says the US military continues a rigorous effort to bring down the expense of V-22s, which currently have a flyaway cost of about $72.1 million, according the US Navy's recently-released fiscal year 2015 budget proposal.

Robinson notes that the V-22's cost per flight hour has dropped 25% since 2009 while its readiness has increased 20%.