Moscow, May 16 (IANS/RIA Novosti): The Russian Sukhoi Superjet 100 that crashed into a mountain in Indonesia, killing 45 people May 9, was a replacement aircraft for one that had been withdrawn due to engine problems shortly before the flight.

A Superjet 100 aircraft with the tail number 95005, which earlier performed demonstration flights in Kazakhstan and Pakistan as part of a six-country tour aimed at wooing potential buyers, was the one originally planned to be shown in Indonesia, the LifeNews TV channel quoted Alexander Tulyakov, deputy president of Russia's United Aviation Corporation (UAC) as saying.

But an engine oil leak revealed during maintenance May 6 forced the show organisers to replace the plane with another similar jet, with the tail number 95004, Tulyakov said.

This resulted in organisers having just a few hours to prepare the plane for the flight, he said.

A spokesperson for the Sukhoi Corporation, which designed the plane and is part of UAC, confirmed that the plane was replaced, but did not name the reason.

All 45 people on board the Superjet 100 were killed when the plane slammed into a steep side of Mount Salak near Jakarta shortly after take-off on a demonstration flight.

Russia's acting Deputy Prime Minister Dmitry Rogozin said experts believe "human factor" was the most probable cause of the fatal crash.

UAC head Mikhail Pogosyan said it was premature to say if pilot error was to blame.

A search operation for victims' bodies continues despite difficult weather and terrain at the site of the crash. Indonesian aviation officials have said the investigation of the crash may take up to a year.