The US Air Force (USAF) has decided to upgrade 300 to 350 F-16C Block 40 and 50 fighters to extend their service life, air force operations deputy chief lieutenant general Herbert Carlisle said.

The upgrade will involve installation of new avionics and increase the airframe life from 8,000 to 10,000 hours.

Defense News has reported that the funding for the modernisation plan will be accounted from the fiscal 2012 budget.

The modernisation is also expected to help the USAF to maintain its existing arsenal of tactical fighters prior to the F-35 Lightning II joint strike fighter (JSF) becoming operational.

The F-35 is likely to be operational in 2018 and will be fielded to Air National Guard units.