Zhukovsky (Russia), Aug 20 (RIA Novosti) The Russian Air Force chief Thursday acknowledged faults in the engine of the fifth-generation fighter jet currently being developed in the country.

The Advanced Front-Line Aviation Complex plane is set to replace the Russian Air Force's fourth-generation fighters, namely, the Su-27 Flanker and the MiG-29 Fulcrum.

Speaking at the MAKS air show near Moscow, Russian Air Force Chief Alexander Zelin said: 'The aircraft will use Saturn engines. There are problems, I admit, but research is continuing.'