(Adds Kosovo negotiations, paras 19-20))

By Jeff Mason and Thomas Krumenacker

HEILIGENDAMM, Germany, June 7 (Reuters) - World leaders agreed on Thursday to pursue substantial but unspecified cuts in greenhouse gases and work with the United Nations to clinch a new deal to fight global warming by 2009.

The agreement, sealed at a G8 summit on the Baltic coast, binds the world's largest polluter, the United States, more closely into international efforts to curb the gases scientists say are causing dangerous changes to world weather patterns.

But it does not commit the club of industrialised nations -- Britain, Canada, France, Germany, Italy, Japan, Russia and the United States -- to the firm emissions reduction targets that the summit host, German Chancellor Angela Merkel, had wanted.

U.S. President George W. Bush has refused to sign up to numerical targets before rising powers like China and India make similar pledges. Convincing them to join the U.N. process will be crucial to reversing a rise in global temperatures.

Bush and Russian leader Vladimir Putin met face-to-face in Heiligendamm for the first time since an ugly diplomatic row erupted over U.S. plans to put parts of a missile shield in central Europe.

At the meeting, Putin appeared to catch Bush off guard with a new proposal that Washington and Moscow jointly use a radar system in Azerbaijan as an alternative to the disputed U.S. plan to base parts of a shield in the Czech Republic and Poland.

"We can do this automatically, and hence the whole system which is being built as a result will cover not only part of Europe but entire Europe without an exception," Putin said.

He said the plan would mean Russia did not need to follow through on a threat to train missiles on Europe.

Protests by anti-globalisation activists continued around the venue, with demonstrators blocking road access and stopping a steam train meant to shuttle officials to and from the elegant 19th century seaside hotel where leaders met.

Police patrol craft rammed two inflatable speed boats that breached a security zone around the venue, tipping environmental activists into the Baltic and injuring three of them.

GLOBAL WARMING

On global warming, the G8 agreed that "resolute and concerted international action" was urgently needed, vowing to stem a rise in greenhouse gases, followed by "substantial" reductions.

Leaders also said they would pursue a new global climate deal by 2009 to extend and broaden the Kyoto Protocol. The final text noted that the EU, Canada and Japan all wanted emissions halved by the middle of the century -- a sign of the split over targets advocated by Merkel.

Under the deal, new climate proposals unveiled by Bush last week would be integrated into the established United Nations process -- a key demand of European countries.

The language represented a partial victory for Merkel, who spent months pressuring the United States, the only G8 country not to sign up to Kyoto, to compromise.

"It's a very positive outcome," Yvo de Boer, the head of the U.N. Climate Change Secretariat in Bonn, told Reuters.

"But bear in mind that this is a G8 conclusion and there are one or two other countries in the world who have to commit to a launch in Bali," he said, referring to a December U.N. meeting in Indonesia where talks will begin to extend Kyoto beyond 2012.

British Prime Minister Tony Blair, who put the climate issue on the global agenda at a G8 summit two years ago, hailed the deal as a "major step forward" and European Commission President Jose Manuel Barroso said Bush had shown "real flexibility".

However, French President Nicolas Sarkozy was less enthusiastic: "If you want me to say that we could have done better then, yes. I want to speak frankly."

G8 diplomats tackled the impasse over the future of Kosovo late on Thursday, with France pushing a plan to delay a U.N. vote on the Albanian-dominated province's independence in exchange for Russia agreeing not to veto the outcome.

Russia backs Serbia's insistence it retain sovereignty over the province, which rebelled against Belgrade's harsh rule in 1998-9. The West regards independence as inevitable and fears delay will stoke violence in the southern Serbian region.

As G8 countries finalised pledges of aid for Africa, rock stars Bono and Bob Geldof launched a last-ditch effort to force leaders to honour the commitments made at Gleneagles in 2005.

"The Chancellor (Merkel) has asked us to trust her - and we are tempted, but we cannot risk being let down by the G8 again," Bono said.

(Additional reporting by Gernot Heller, Alister Doyle, Katherine Baldwin, Tabassum Zakaria, Madeline Chambers, Erik Kirschbaum, Caren Bohan, Christian Lowe, Crispian Balmer, Louis Charbonneau, Knut Engelmann)

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