Commercial Aircraft Corporation of China (Comac) is reportedly delaying the maiden flight of C919, China’s first commercial aircraft.

Reuters quoted sources who said the C919 programme is behind schedule and deliveries are likely to be pushed back to as late as 2020.

The first flight of the narrow-body aircraft was originally scheduled for the end of this year, but may be postponed to the first half of 2016.

A source said: "Comac is proceeding extremely cautiously with the first aircraft.

"It is deliberately checking everything…to ensure that there are no safety issues."

"Comac is proceeding extremely cautiously with the first aircraft."

C919 aims to compete with Boeing 737 and Airbus A320.

The first aircraft, which is currently at a sub-assembly facility near Shanghai’s Pudong International Airport, will be equipped with tail, vertical and horizontal stabilisers before being moved to the final assembly plant.

In the coming days, Comac will install two CFM International Leap 1C engines on to the plane, along with systems from Honeywell, United Technologies’ subsidiary Goodrich, Rockwell Collins and Parker Aerospace.

The C919’s components, including fuselage, wings and tail, are being manufactured by subsidiaries of AVIC at their facilities across China.

"There is still a lot of work to do," the source added.

"At the pace that Comac is proceeding, they will only complete the systems integration around end-2015."

Although Civil Aviation Administration of China (CAAC) certification will allow Comac to put the C919 into service, the company is seeking to obtain USS FAA certification for the aircraft, to attract customers from international markets.