European leaders launched Friday a trillion-euro bid to slash dependency on Middle East oil and Russian gas, clearing the way to place nuclear power at the centre of 21st century needs.

At a summit shaken by instability over Egypt's popular revolt and soaring oil prices, the European Union moved to reclaim control over energy supply for the rest of the century with reforms designed to unlock private investment.

The EU is the world's largest regional energy market -- 500 million people and 20 million companies.

Governments committed to a broad sweep of market reforms, linking national and regional electricity grids and gas pipelines by 2014 to allow power to circulate freely and cheaply, from those who produce it and have surpluses to those who don't and need it.

"No EU member state should remain isolated from the European gas and electricity networks after 2015 or see its energy security jeopardised by lack of the appropriate connections," read summit conclusions whose adoption was announced by EU president Herman Van Rompuy on Twitter.

"Beyond the management of today's crisis, we're also laying the ground for a sustainable and job-creating growth," Van Rompuy tweeted.

Island states Cyprus and Malta, as well as Baltic countries whose infrastructure remains tied to the former Soviet Union, feared their needs may be considered too insignificant for the big energy players to invest in costly transmission networks.

But the EU agreed that pooled public money could underpin completion of this so-called 'supergrid' -- although ballpark sums will not be produced until the summer.

Initial European Commission estimates suggested that some 2.5 billion euros ($3.4 billion) could be diverted from unspent EU budgets.

While one EU diplomat said it was "doubtful" that Britain would back such an approach, Prime Minister David Cameron was comfortable with allowing "some limited public finance to leverage private funding," as the summit conclusions specified, provided it comes from cuts elsewhere in the EU budget.

The network development cost over the remainder of the decade is tipped to exceed 200 billion euros.

The other big change, at the instigation of France but firmly backed by the government in London, was to reposition domestically-produced nuclear energy at the heart of the bloc's long-term suppplies.

In a carefully-worded shift in emphasis, alongside investment in renewable energy technologies, EU states will also promote "safe and sustainable low-carbon technologies" -- this including nuclear -- under climate action goals.

This came under attack from ecologists and Poul Nyrup Rasmussen, the head of the Party of European Socialists, as: "Old leaders, with old ideas, simply proposing old energy methods for Europe?s future."

Brussels-based NGO Energy Strategy Center also saw a missed opportunity given a "significant shift currently underway in the climate and energy debate."

It pointed out that, yet again, "China is rapidly becoming a global leader in the technologies of a resource efficient, low-carbon economy."