* Germany, France, Britain among nations exploring tougher goals
* Say want to 'lead from the front'
* Welcome U.N. plan for summit in 2019 (Adds details, reactions)
By Alister Doyle
OSLO, June 21 (Reuters) - More than 20 nations ranging from Germany, France and Britain to Pacific island states said on Thursday they planned to "lead from the front" in setting new, tougher goals by 2020 to cut greenhouse gas emissions under the Paris climate agreement.
They welcomed a decision by U.N. Secretary-General Antonio Guterres to host a summit in September 2019 to review the fight against global warming since almost 200 governments signed up in 2015 for the Paris accord.
"We commit to exploring the possibilities for stepping up our own ambition," the 23 nations said in a statement, issued by the Marshall Islands in the Pacific, about goals for stepping up action by 2020.
"We call on other countries to join us in expressing their desire to lead from the front."
The governments also said in a "Declaration for Ambition" that they would encourage long-term strategies for low emissions and new funds and investment in projects to help goals of the Paris Agreement.
Signatories were Argentina, Britain, Canada, Chile, Colombia, Costa Rica, Denmark, Ethiopia, Fiji, Finland, France, Germany, Maldives, Marshall Islands, Mexico, Monaco, the Netherlands, New Zealand, Norway, Rwanda, Saint Lucia, Spain and Sweden, a statement said.
"This declaration shows that countries understand the urgency of climate action and are actively looking into making bigger, bolder commitments," David Waskow of the World Resources Institute think-tank, wrote in a statement.
The Paris climate agreement obliges countries to set new climate goals every five years as part of a goal of phasing out polluting fossil fuels this century.
The nations said they would work in the light of a U.N. report by leading climate scientists, due for publication in October, about ways to limit a creeping rise in global average temperatures that is causing heat waves, downpours and droughts.
A leaked draft of that report says warming is set to exceed 1.5 degrees Celsius (2.7°F) above pre-industrial times, the strictest goal under the Paris Agreement, by around 2040 unless governments take "rapid and far-reaching" measures.
China, the European Union, India and Russia, the top emitters of greenhouse gases which support the Paris accord, were not among nations signing the declaration. It is preliminary with other nations welcome to sign up.
The landmark Paris agreement has been weakened by a decision by President Donald Trump to pull the United States, the number two emitter, out of the accord. Trump doubts mainstream scientific findings that man-made greenhouse gases are the prime cause of warming and wants to promote the coal industry.
By contrast, small island states say that a thaw of ice worldwide will raise sea levels and swamp their nations.
"If we do not raise global ambition by 2020, it will be too late for my island nation," Hilda Heine, President of the Marshall Islands, said in a statement.
(Reporting By Alister Doyle; Editing by Toby Chopra and Andrew Heavens)
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