Europe's energy consumers, already facing big rises in their gas and power bills, will be the losers if more mergers in the utility sector go ahead as these will reduce competition even further, analysts say.
German utility giant launched a surprise takeover bid for Spain's Endesa, followed a day later by news Italy's largest utility Enel might make an offer for France's Suez.
The head of France's EDF said his company was ready to consider major acquisitions and was following developments in Benelux and Spain.
These are the latest steps in a wave of consolidation in the industry which could lead to the creation of as few as three large utilities in the region.
The emergence of just a handful of giant suppliers will reduce competition as they will concentrate on protecting their own markets and be reluctant to battle against each other, said Jonathan Stern from the Oxford Institute for Energy Studies.
"As long as big people keep getting bigger, then there will be less competition... they won't fight it out against each other," Mr Stern said.
Stern said studies showed there need to be six players, but ideally 10, to have proper competition in a market.
The European Union's Commission Commissioner Neelie Kroes warned gas and power suppliers that they faced a new antitrust crackdown to break their industries open to competition.
"Given the mood music flying around, I suspect people in Brussels will find it irresistible to get involved (in these deals) in some fashion," Nick White, head of the energy practice at Arthur D Little, said.
Consumers across Europe have seen big jumps in their gas and power bills in the last year. Companies blame record oil prices and high wholesale energy costs but consumers, especially in Germany, point to the dominance of the country's two largest suppliers - E.ON and its rival RWE.
This week utilities, including E.ON, RWE, EDF and Britain's Centrica, have reported bumper profits.
Centrica, the UK's largest gas supplier, last week hiked its bills by a stinging 22 per cent.
E.ON's CEO Wulf Bernotat has predicted that there could be just three large utilities in Europe - his company, French firm Electricite de France and Italy's Enel.
"There ought to be significant synergies and cost reduction potential with these large companies. The question is whether regulators are sufficiently adept and strong to make sure the savings are passed on to consumers," Mr White said.
"If the regulators don't act in consumers' interest, then consumers may pay a heavy price."
The large utilities have already succeeded in chopping Europe's power market up into regional blocs, with limited electricity and gas flows across borders.
"Physically it is not integrated enough, there is not enough liquidity in terms of the wholesale power and gas markets," Fabrizio de Candia, director of European power at Cambridge Energy Research Associates said.
The first step towards a competitive single market is the creation of regional markets as is happening to some extent in northwest Europe and in the Nordic countries, he said.
But for a pan-European energy market to emerge there needs to be more transparency and competition in the wholesale markets and there is little sign of this happening soon, he said.
"Basically the big players are carving up various parts of the market," Mr de Candia said.