Unless power grid operators are forced to invest more in transmission networks, Europeans can expect a repeat of the November blackout that left millions of people in six nations without power, the European Commission said Tuesday.

On Nov. 4, 2006, a sudden weekend surge in Germany's demand for electricity due to freezing weather plunged much of Europe into blackness as France and other power exporting countries found their grids overtapped.

The power outage left 10 million people -- half of them in France -- in the dark and cold. Belgium, Britain, Germany, Italy and Spain were also affected.

Authorities said then that the incident underscored the urgent need to create a coordinating agency for the entire continent.

"Europe should draw lessons from blackout"

The final report, which covers operators in 23 European countries, endorsed that view, the Commission said.

"Europe should draw lessons from this blackout that left millions of Europeans in various member states without electricity and develop stronger network security standards," said EU Energy Commissioner Andris Piebalgs.

The report said the power cuts were due to German energy giant E.On's poor security systems. However, E.On was not alone in causing the power cut, the EU head office concluded.

It said its failings were just one of three main reasons cited in a report published Tuesday by a power grid operators' group, the Union for the Coordination of Transmission of Electricity.

Firstly, E.ON Netz, the system operator at the origin of the fault, did not have the necessary security procedures in place and "did not even have the full technical tools to verify that the system operated within the security limits."

The UCTE report also said there was a communication breakdown that meant the German transmission operator, which controls the amount of power in the network, did not properly inform counterparts in other countries about what it was doing.

Thirdly, there was a lack of investment to improve the reliability and the operation of the grid, the report said.

"These causes confirm the Commission's analysis in favor of common action for ensuring the security of electricity supply throughout the European Union," the EU's executive arm said.

EU says urgent action needed

The EU's executive arm called for urgent action to prevent a repeat of the November power failure.

In addition to stepping up investment in the energy sector, the EU said regional system operators needed to take control of the grid, saying this would require "effective unbundling" or breaking up the supply chain by taking this function out of the hands of the companies that generate and supply power.