Italy's prime minister has said Europe needs a central power authority to prevent the kind of blackouts that left swathes of West Europe without energy.
Energy demand has been rising in Europe as winter nears
An overload in Germany's power network triggered outages leaving millions without electricity on Saturday night.
Romano Prodi said there was a "contradiction" in having a unified power network but no central authority.
Power failed first in Cologne, Germany, before shutting down across parts of France, Italy, Spain and Austria.
Belgium, the Netherlands and Croatia were also affected.
"My first impression is that there is a contradiction between having European networks but not having a central European authority. It is somewhat absurd," Mr Prodi said.
German utility provider E.ON said early investigations suggested the supply failures were caused by overloads in the power network in northwest of the country, according to Reuters.
The power outages were quickly restored in most cases but in some of the worst cases:
In Paris, firefighters responded to nearly 40 calls from people stuck in lifts as the city lost power
Scores of trains were delayed in Germany's industrial Ruhr region for up to two hours
The Italian regions of Piedmont, Liguria and Puglia lost energy overnight between 2100 and 2200 GMT
In Spain, power was lost in the cities of Madrid, Barcelona, Zaragoza and parts of the Andalucia region.
European blackout risk
E.ON said the power failures may have been linked to a line across a river being switched off to allow a ship to pass through safely, Reuters reported.
France was one of the worst affected, with five million losing power mainly in the east of the country and the capital, Paris, and its suburbs.
"We weren't very far from a European blackout," a senior director with French power company RTE said.
Most electricity supplies were restored within two hours of the outage, and so far no injuries or accidents have been reported.
The worst recent power blackout struck Italy in 2003, plunging the country into darkness for 18 hours between 28 and 29 September.