MOSCOW, May 26 (RIA Novosti) - Anatoly Chubais, the chief executive of Russia's Unified Energy Systems (UES), is to be questioned at 4 pm Moscow time, a spokesman for the Moscow prosecutor's office said.

"Moscow prosecutors have opened a criminal case on "abuse of power in profit-making organizations" and "negligence" after the power blackout affected companies, organizations, and dwelling areas, which caused serious damage and grossly violated the rights and legal interests of people, organizations and the state," said the spokesman.

According to him, this qualification requires careful investigation into the work of technical personnel and leadership of the energy sector, and also the way public officers and representatives of regulatory bodies behaved.

"The investigative group is now questioning witnesses, confiscating and studying relevant documents," the spokesman said.

The damage inflicted upon the city, infrastructure and the people is being estimated.