A Russian government commission looking into the crash of the Phobos-Grunt Mars probe says engineering flaws were the main cause of its failure, the head of the Russian Space Agency Roscosmos, Vladimir Popovkin said on Thursday.

There was speculation earlier this week that the crash of the 1.2 billion ruble ($400 million) could have been caused by a powerful electromagnetic emission from a U.S. radar.

Popovkin however said that the U.S. radar is viewed "only as one of the causes."

"The main causes were the errors during production and test works, as well as the engineering flaws," Popovkin said.

Roscosmos is expected to hold tests to see whether the probe was affected by U.S. radars, which may involve NASA specialists, Popovkin added.

Phobos-Grunt, Russia's most ambitious planetary mission in decades, was launched on November 9 but it was lost due to a propulsion failure and fell back to Earth on Sunday.

According to NASA, Russia has failed in all 17 of its attempts to study the Red Planet close-up since 1960. The most recent failure before November 2011 occurred in 1996, when Russia lost its Mars-96 orbiter during launch.

Source: RIA Novosti