"Expressing grief over the [air crash] victims and conveying condolences to their relatives and close ones, I decree to declare July 10, 2006 a day of mourning in the Russian Federation and to lower the state flags of the Russian Federation," the presidential decree says.

According to preliminary data, a fault of the brake hydraulic system caused a Siberia airbus crash Sunday, claiming the lives of more than 100 people, a source in the investigative commission said.

"The data available to the commission indicate that after landing the aircraft's brake system failed, causing the failure of the system's other mechanisms. As a result, the aircraft became uncontrollable after landing," the source said, RIA Novosti reports.