The scramble by some of Europe's biggest energy companies to forge megamergers before a full opening of the market next year will fuel a tectonic shift in the energy landscape of the entire Continent, creating as few as three or four champions that could monopolize the sector within a decade, according to analysts.

Flush with cash from record energy prices, companies like E.ON of Germany, Suez of France and Gazprom of Russia say they are positioning themselves to be ready when the European Union fully opens energy markets to competition in July 2007.

E.ON's chief executive, Wulf Bernotat, said when announcing his company's hostile bid for Endesa of Spain in February that "a combined company will create a leading competitive player with operations in all key European countries." He argued that it would be an "important step toward creating a single European energy market."

But industry analysts warn that competition is likely to be suffocated once some of these mergers are completed. "The way the energy sector is developing, I could well see three or four big players dominating the market and setting the agenda over the next 10 years," said Claudia Kemfert, a professor and energy expert at the German Institute for Economic Research in Berlin.

Kemfert said that within a decade, the energy market in Europe would be dominated by three companies: E.ON Ruhrgas, a German gas distribution company, which would dominate the natural gas sector; Enel, the Italian electricity and gas company; and Electricite de France. Gazprom, the Russian state-owned energy giant, would also be a major player in the natural gas sector. Gazprom already provides a quarter of the European Union's energy needs.

E.ON Ruhrgas, Electricite de France and Enel are already in a very strong position, all having subsidiaries in Western and Eastern Europe. With a combined market capitalization of 189 billion, or $224 billion, analysts say, the three could block attempts by smaller companies to enter the market by locking industrial clients and consumers into long-term contracts and hindering access to their distribution networks.

Jonathan Stern, director of gas research at the Oxford Institute for Energy Studies, said proposed mergers between Suez and Gaz de France, and between E.ON and Endesa, would not create a healthy competitive environment.

"The mergers are a contradiction, in terms to competition," Stern said. "They hinder it. I don't see how this contradiction can be resolved. It gives competition no chance whatsoever. It makes a mockery of the EU's Lisbon Agenda, which was supposed to make Europe competitive."

Kemfert, the energy expert, said prices would be dictated by the largest companies. "These mergers will be bad for competition and bad for the customers," she said.

Indeed, last week the British energy supplier Powergen, which is owned by E.ON, said it would raise electricity rates 18.4 percent and natural gas prices by 24.4 percent. And in Germany, the Federal Statistics Office said Thursday that energy prices had risen sharply over the past year, with the price of natural gas for domestic consumers up 19 percent through January, and electricity up 4.2 percent.

The European Commission, which complained about the lack of openness in energy pricing last month, put a brave face this week on the rush of mergers.

"The attempts to create these mergers show that companies realize the EU is going toward an energy market," said Ferran Tarradellas, a spokesman for the EU energy commissioner, Andris Piebalgs. "Competition in the energy sector is a growing reality."

But Stern and Kemfert said the commission was almost powerless to encourage competition. Only last month, the EU competition commissioner, Neelie Kroes, said that the natural gas sector lacked competition and openness and that much of the market was concentrated among only a few suppliers.

The emergence of even more powerful players could in turn undermine or even wreck plans by the European Union to introduce a fully competitive and open energy sector next year. Analysts agree that if some of the proposed mergers take place this year, they would seriously weaken the commission's efforts at opening markets. The merger rush also happens to coincide with an intense focus on energy security and competition. The European Union's energy commission is preparing a special policy report to consider how to create a more secure, competitive and sustainable sector for Europe. The paper is to be published next week.

This month, an EU summit meeting will focus on energy security, with new member states from Eastern Europe expected to call for a coherent and united energy policy. A Group of 8 summit meeting will place energy high on its agenda when leaders meet in St. Petersburg in July.

The focus on energy comes in the wake of growing concern in the European Union over the reliability of energy supplies, notably from Russia, which sends the bloc 25 percent of its energy needs.

When Gazprom stopped supplies to Ukraine in January over a price dispute, it led to shortfalls for European countries as well because the gas that Russia sends to Europe passes through a pipeline controlled by Ukraine.

President Vladimir Putin of Russia, host of the G-8 meeting, sought to reassure the Europeans on Wednesday by calling for an energy security policy.

"Energy egotism is the road to nowhere," Putin said in a 1,700- word statement released by the Kremlin. "We are duty bound to leave for those who follow us a world energy 'architecture' which will protect them from conflicts, from unconstructive forms of struggle over energy supply."