Athens remains at risk of another mass power blackout during next month's Olympics if electricity consumption stays high because of scorching heat, a chief overseer of Greece's electricity grid said Tuesday.

The warning was part of a nationwide investigation by engineers and experts seeking answers to Greece's worst power failure in decades, which crippled the southern half of the country for hours Monday and stunned Olympic organizers. The Games begin Aug. 13.

The overall conditions that knocked out power to at least 7 million people cannot be fundamentally corrected before the Games, said Evangelos Lekatsas, chairman of the Hellenic Transmission System Operators, which regulates the nation's flow of electricity. A heat wave and heavy air-conditioner use are important factors that could create another blackout during the Games.

A detailed explanation of the blackout is not yet available. But Lekatsas and others offered a general picture: A major malfunction occurred as the system tried to compensate for a crippled generating station near Athens. Millions of air conditioners were in use as the temperature reached 104 degrees.

No major generating plants have been built in the Athens area for the Olympics, but several smaller stations are planned. In addition, five new substations are expected to begin operating next month to help distribute electricity.

Greek officials are counting heavily on nature to help out. According to 13 years of data, the temperatures and electricity consumption are normally at their peak in Athens in the first two weeks of July, Lekatsas said. August tends to be a bit cooler, with average highs in the low 90s.

Government leaders and power grid operators held emergency meetings to devise strategies to avoid a failure during the Olympics. But there was also blame trading going on. Government officials said the blackout was caused by human error. Greece's Public Power Corp. -- an Olympic sponsor -- said the fault rested with the state-run company that regulates the grids.

All Olympic venues have independent generators and other auxiliary power systems, but not all were in operation Monday, said Claude Philipps of Atos Origin, the technology firm handling results and other information distribution during the Games.

"We have all the data here, to have second by second what happened. . . . We need more than one month to have a very clear picture of everything that happened," Lekatsas said.