Russian space officials say this month's launch failure of a Proton rocket was due to excessive vibrations in the engine of the rocket's third stage.

Igor Komarov, head of the Roscosmos space agency, told reporters Friday that the vibrations came from a rotor shaft and were due to the material it was made of. He said using a different material to solve the problem would not be excessively costly, but he didn't specify an amount.

The May 16 launch failure, which resulted in the loss of a Mexican communications satellite, came a few weeks after a Soyuz booster rocket broke down as it was trying to send an unmanned supply ship to the International Space Station. The cargo ship later fell to Earth, disintegrating in the atmosphere.