MOSCOW (Reuters) – Russia will postpone the maiden flight of its first fifth-generation fighter aircraft until 2010, the state news agency RIA quoted Deputy Prime Minister Sergei Ivanov as saying yesterday.

Russian government and industry officials had repeatedly said the warplane, seen as Moscow's challenge to the US-built Raptor, would make its first flight by the end of 2009.

"Test flights will begin in 2010," Ivanov, who oversees Russia's military-industrial complex, told reporters during a visit to a defence industry centre in the Ural Mountains.

The fifth-generation fighter is being designed and built by military and civilian aircraft manufacturer Sukhoi.

A Sukhoi spokesman declined to comment on Ivanov's statement.

Sukhoi is Russia's largest exporter of military planes, accounts for a quarter of Russia's annual arms sales and has a portfolio of foreign orders worth billions of dollars. India is its main client.

Russia's once-formidable air forces badly need new planes, even if they are less sophisticated than the fifth-generation one, since many of the Soviet-built aircraft are old and unsafe.

The Moscow-based Centre for Analysis of Strategies and Technologies (CAST) has said possible delays in the first flight of the new fighter have little significance in themselves.

What is more important is that there could be at least 10 years between the first flight of the prototype and the start of commercial production, CAST has said.

Fifth-generation jets, such as the U.S. F-22 Raptor stealth fighter which first flew in 1997, are invisible to radar and boast "intelligent" on-board flight and arms control systems, and supersonic cruising speeds. (Reporting by Dmitry Solovyov; Editing by Guy Faulconbridge)

REUTERS