Officials said Thursday that 72 workers at the Charles de Gaulle-Roissy international airport had been stripped of their security clearance since May 2005 for suspected links to Islamic extremists and other fundamentalist groups.

"We are going to call for a strike at the end of November and for a rally outside the prefecture in Roissy," which took the decision to remove the staff badges, said Didier Frassin, the head of the main CGT union at the airport.

Seven unions were to hold a meeting on Tuesday to decide whether to back the strike call and what further action to take.

Unions have already filed a complaint for discrimination and the French anti-discrimination agency HALDE is also investigating the matter.

Jacques Lebrot, the Roissy deputy prefect, said Thursday the workers had been "linked to fundamentalist movements with potentially terrorist aims."

The "great majority" were linked to an "Islamist movement", although badges were also taken away from "just under a dozen" people suspected of links to Sri Lankan Tamil Tiger rebels as well as from one Sikh worker, he said.

One was allegedly in regular contact with an associate of the British "shoe-bomber" Richard Reid, who was convicted of trying to blow up an American Airlines Paris to Miami flight in 2001.

But union leaders say many have been unfairly targeted.

"The deputy prefect is just making allegations, not proving anything. We are waiting for proof of the threat these employees represent - not just shock statements," said Philippe Decrulle, CFDT union leader at Air France.

"It is all totally vague, they have nothing to go on, it's a scandal," said Daniel Saadat, a lawyer for a group of workers who have appealed the decision.

But Interior Minister Nicolas Sarkozy said officials were obliged to withdraw the security clearances as a "precaution".

"Each time we withdrew a badge, it was because we had elements that allowed us to do so. Me, I have a duty which is a duty of precaution. In the Roissy zone, you can get close to planes, there are millions of passengers," he said.

"It's quite right that the police services conduct inquiries and only certify those people we are certain about."

He also rejected the argument that ordinary Muslims were being discriminated against purely on the grounds of their faith.

"The Muslims in France have nothing to do with this. Islam can be practised without a problem. Where there is a problem is with extremism," he said.

Lebrot said another 40 employees at the airport were currently being investigated as posing a possible security risk.

Sixty-eight others have been cleared since the start of the investigation in May last year. Five who lost their badges later regained them after "bringing new elements" to the attention of the authorities, he said.

A nationalist French politician, who created a stir in April for publishing a book in which he claimed the airport was infiltrated by Islamic extremists, said his contentions had been borne out by the authorities' decision.

Philippe de Villiers, head of the right-wing Movement for France (MPF) party, said on Friday he believed Islamic extremists could still be working at the airport despite the recent crackdown.

"There are networks of baggage handlers who are Islamic extremists, that's now been shown," he told RTL radio. "There were some, and there probably still are some," he said.

"When I brought my book out, a lot of people told me 'It's probably exaggerated'. Today, we see it's true and that it's scary."

Authorities said it underscored an urgent need to create a coordinating agency for the entire continent.

Swathes of France, Italy, Spain, Belgium and the Netherlands went dark for up to an hour late Saturday as cold Germans rushing to switch on heaters sucked up electricity from Europe's interconnected networks.

Automated switching protocols meant the grid in France -- a net exporter of electricity to Germany and other countries due to its fleet of nuclear power stations -- was massively called on to meet the shortfall in Germany.

"It all happened in several seconds," said Pierre Bornard, a senior executive at RTE, a subsidiary of the French electricity giant EDF that handles electricity distribution.

In France, more than five million people, or nearly one-tenth of the country, were left without power, especially residents of Paris and its suburbs.

"We weren't very far from a European blackout," Bornard said.

Winter temperatures that fell to below freezing in parts of Germany, Europe's most populous country, triggered the incident.

The west German city of Cologne was the first place to go black as strained power networks failed to shift electricity supplies to German consumers. The failure of two German high-voltage transmission lines compounded the problem.

The Cologne-Bonn airport was affected, but generators were started to prevent disruptions to air traffic.

A spokesman for the private Germany energy company EWE admitted that the German network suffered a "spike" it was unprepared for.

The automatic switching by France's EDF network simply transferred the problem to that country, and beyond.

France's high-speed train services were disrupted, with delays on a dozen lines.

Various parts of Italy were affected, particularly the northwestern Piedmont area, which lost electricity for around 30 minutes.

Several areas of Spain were also hit, including Madrid, and the eastern Catalonia and Valencia regions, according to Spain's REE company.

There were no immediate reports of any injuries as a result of the blackout.

Bornard said that, as the huge imbalance was detected, computers in the power networks simply shut down part of the output. "It was the only way to avoid a complete meltdown," he said.

RTE said 5,200 Megawatts -- nearly 10 percent of the output at the time -- were "immediately interrupted".

Italian Prime Minister Romano Prodi said Sunday that a common European authority was needed to oversee electricity distribution.

"We all depend on each other, but we can't help each other without a common authority," he said, according to the Italian news agency ANSA.

"It's totally contradictory to have several European connections and not have a single European authority," he said.

The reliability of Europe's electricity system has been undermined in recent years as consumption has grown without corresponding investment.

Frequently during periods of extreme cold or heat, the power networks in European countries come under pressure, with transmission companies forced to take special measures.

The last major outage in Europe occurred in September 2003, when virtually all of Italy and part of the Swiss city of Geneva were left without power for up to 20 hours.

A surge Saturday in electricity demand in Germany due to cold weather triggered blackouts in some parts of the country but also in France, Italy and Spain. A number of the power cuts lasted for around 30 minutes.

Europe's energy grids frequently come under pressure from excessive demand during periods of extreme cold or heat, forcing electricity companies to take special measures.

"Whilst these blackouts lasted for relatively short periods of time, they are unacceptable," Piebalgs said. "Energy security is better delivered through a common European approach rather than 27 different approaches."

He said that he asked Europe's Transmission System Operators (ETSO) to quickly pin-point the cause of the problem and draw up measures to ensure that it does not happen again.

He also said that he wanted to set up a "mechanism" to ensure that these and other energy security standards, to be drawn up by a working group, are made binding on electricity network operators.

"That alone cannot explain the problem. The disturbances only occurred half an hour after the shutoff," E.ON spokesman Christian Schneller told Bayerischer Rundfunk radio.

E.ON chairman Klaus-Dieter Maubach rejected suggestions that under-investment in the network in Germany - home to 82 million people - was to blame for the power cut, as suggested by Environment Minister Sigmar Gabriel.

"The networks are in good condition," he said.

The power outage left 10 million people - half of them in France - in the dark and cold.