Tests carried out by Russian space agency Roscosmos have ruled out the possibility a U.S. radar could be linked to the failure of the Phobos-Grunt Mars probe, Roscosmos head Vladimir Popovkin said on Thursday.

In an interview with the Ekho Moskvy radio station, Popovkin said an experiment to test the radar's impact showed no link between the failure of the Mars mission and the alleged electromagnetic emission from a U.S. radar in the Pacific Ocean.

The U.S radar theory first appeared in mid-January when unidentified space officials told the Kommersant daily that U.S. radar could have been behind the mishap.

NASA dismissed the idea and refused to take part in the tests.

Among the possible causes of the crash, Popovkin on Tuesday named cosmic radiation that triggered a glitch in the on-board computer system and defective microchips imported from abroad.

Phobos-Grunt, Russia's most ambitious planetary mission in decades, was launched on November 9 but a propulsion failure left it stuck in Earth orbit. It fell back to Earth on January 15.

Popovkin previously suggested that certain forces in the Western Hemisphere, which is a shadow zone for Russia, might be shooting down Russian spacecraft.

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.