The US Air Force is concerned that software development and production issues will delay its plan to begin using new F-35 fighter jets in April 2016.

The possible F-35 delivery delay has been revealed by the defence official in charge of the F-35 programme, vice admiral David Venlet, after a comprehensive review of the programme.

US Air Force general Norton Schwartz said the air force will consider upgrading its existing F-16 fighters through structural modifications and radar and avionics improvements if the F-35 delivery is delayed.

The general said the air force variant of the F-35 fighter jet has, however, performed better in testing and development than the Navy and Marine Corps’ versions.