About 80 percent of all air crashes happening in Russia were caused by human errors, Russian Prosecutor General Yury Chaika said Wednesday.

"An inspection indicated that the existing system of assigning qualifications to employees in the aviation sector and allowing them to work does not comply with the requirements of national air legislation or international standards," Chaika told the Federation Council, or the upper house of the Russian Parliament.

According to Chaika, sometimes the aviation authorities allowed inexperienced pilots to conduct flights and that the pilots training institutions "not always" have the necessary human resources or equipment.

"For several years the certificates have been issued to pilots with no required flight hours and as a result, the pilots with actual experience of 60 hours instead of the necessary 150 were allowed to transport passengers," Chaika said.

He added that the Prosecutor's Office identified "numerous decisions" by the aviation authorities to prolong the certificates of airlines despite their unstable financial situation and insolvency which has led to the "massive violation of passengers' rights."

According to the official, during peak seasons Russian airlines routinely oversell tickets which led to massive flight delays or cancellations as the airlines have no reserved aircraft.

In 2011, six air crashes occurred in Russia with 97 people killed, which accounted for more than one fifth of all air crashes in the world.