Sukhoi Civil Aircraft is set to postpone delivering its Sukhoi Superjet 100 regional aircraft indefinitely due to a further delay in the flight test programme.

“We do not rule out that supplies to launch customers will begin later than planned originally,” Alexei Fyodorov, chief of the United Aircraft Corporation, which comprises Sukhoi, told media in Moscow.

Citing logistics difficulties and the delay in starting Superjet 100 flight trials, he added: “All will depend on when the certification programme completes.”

Under the original plan, certification flights, involving four Superjet 100 test aircraft, were scheduled to begin last year and complete in 2008.

Sources close to the situation say Sukhoi has built only one example at its factory KnAAPO. The maiden flight is expected to take place by the end of April – almost a half year behind the original timetable.

Russian flag-carrier Aeroflot is a launch customer for the Superjet 100 with a firm order for 30 aircraft plus options on 15. It should take first delivery in November and the next one in December.

But Fyodorov says the delay will not incur penalty payments by the manufacturer as its contract with Aeroflot stipulates a possibility of some leeway in the supply schedule.

A spokesman for Aeroflot has declined to comment in the absence of an official memo about the potential delay from Sukhoi.

The prototype Superjet was originally scheduled to start flight certification tests before 2007, but is now expected by the end of April. The schedule slip was partly attributed to flight test delays for the SaM146 powerplant, which entered testing months late in December aboard an Ilyushin Il-76.