U.S. Secretary of State Hillary Clinton told an audience on Friday "never waste a good crisis", as she highlighted the opportunity of rebuilding economies in a greener, less energy intensive model.

Highlighting Europe's unease the day after Russia warned that gas exports to the EU via Ukraine might be halted, she also condemned the use of energy as a political lever.

Clinton told young Europeans at the European Parliament global economic turmoil provided a fresh opening: "Never waste a good crisis ... Don't waste it when it can have a very positive impact on climate change and energy security."

Europe sees the United States as a crucial ally in global climate talks in Copenhagen in December, after President Barack Obama signalled a new urgency in tackling climate change, in stark contrast to his predecessor George W. Bush.

Europe has already laid out plans to cut carbon dioxide emissions to about a fifth below 1990 levels in the next decade, while Obama has proposed a major shift towards renewable energy and a cap and trade system for CO2 emissions.

But with many countries in the grip of a punishing recession, some question whether businesses can muster the hundreds of billions of dollars needed to cut carbon emissions.

"Certainly the United States has been negligent in living up to its responsibilities," said Clinton, on her first visit to Europe as secretary of state.

"This is a propitious time ... we can actually begin to demonstrate our willingness to confront this.

POLITICAL LEVER

Many politicians argue that the economic crisis, energy security issues and climate change can all be dealt with in a "New Green Deal", replacing high-carbon infrastructure with green alternatives and simultaneously creating millions of jobs. "There is no doubt in my mind the energy security and climate change crises, which I view as being together, not separate, must be dealt with," Clinton added.

She attacked the use of energy as a political weapon, echoing Europe's worries after repeated spats between Russia and gas transit country Ukraine hit EU supplies in recent years.

"We are ... troubled by using energy as a tool of intimidation," she said. "We think that's not in the interest of creating a better and better functioning energy system."

Clinton is set to meet Russian Foreign Minister Sergei Lavrov for dinner in Geneva in the hope of improving relations after a post-Cold War low during Bush's presidency.

The latest cuts to Russian gas exports in January forced the closure of factories, hospitals and schools in Eastern Europe and left thousands of snowbound households shivering.

A new row between Ukraine and Russia appeared to have been averted on Thursday after state-owned Gazprom said Ukraine had settled payments at the heart of the disagreement.

But European leaders were rattled by the warning of cuts to supply by Russian Prime Minister Vladimir Putin.

Watch the VIDEO: Clinton: "Never waste a good crisis"