* Joint statement on Paris agreement main aim of meeting
* Premier Li to meet top EU officials in Brussels
* Both sides to pledge to address steel crisis - draft (Updates after Trump announces leaving climate accord)
By Robin Emmott and Robert-Jan Bartunek
BRUSSELS, June 1 (Reuters) - China and the European Union will seek on Friday to save a global pact against climate change from which U.S. President Donald Trump said he will withdraw.
As China emerges as Europe's unlikely global partner on areas from free trade to security, Premier Li Keqiang will meet top EU officials at a summit in Brussels that will also address North Korea's missile tests and global steel overcapacity.
Speaking in Berlin, Li underlined strong support for the 2015 Paris climate change accord from China, which overtook the United States as the world's biggest emitter of greenhouse gases in 2007.
"China will stand by its responsibilities on climate change," he told reporters after meeting German Chancellor Angela Merkel and before flying on to Brussels.
In a statement backed by all 28 EU states, the European Union and China will commit to full implementation of the Paris Climate Agreement, EU and Chinese officials said.
The joint statement, the first between the China and the EU, commits to cutting back on fossil fuels, developing more green technology and helping raise $100 billion a year by 2020 to help poorer countries cut their emissions.
"The EU and China consider climate action and the clean energy transition an imperative more important than ever," the statement, by European Council President Donald Tusk, European Commission President Jean-Claude Juncker and Li, will say.
"The increasing impacts of climate change require a decisive response," they will say.
China asked that the annual summit, normally held in mid-July, be brought forward to press home President Xi Jinping's defence of open trade at the World Economic Forum in Davos in January in response to Trump's protectionist stance .
Miguel Arias Canete, the EU's energy commissioner, said in a statement after Trump's announcement that the European Union deeply regretted the decision but would seek new allies in the fight against climate change.
"We see the Paris Agreement and the low-carbon transition for what it is, the irreversible growth engine of our economies and the key to protecting our planet," Canete said.
While China needs EU technical know-how to fight the pollution blighting its cities, the European Union is looking to Beijing to take action against emissions blamed for increased droughts, rising seas and other affects of climate change.
In a broader final communique focusing on a range of other issues, Li, Juncker and Tusk are expected to commit to free trade and reduce a global steel glut that Europe and the United States say is an attempt by China to corner local markets.
The EU and China will seek to "refrain from all forms of protectionism and uphold free and rules-based trade", the leaders will say in a 60-point statement, according to a draft. They promise to "address steel overcapacity at its roots".
By far the world's top steel producer, China's annual steel output is almost double the EU's total production. Western governments say Chinese steel exports have caused a global steel crisis, costing jobs and forcing plant closures.
The warmer EU-China relationship, partly spurred by Trump, has developed despite a long-running EU spat with Beijing on what Europe sees as China's dumping of low-cost goods on European markets.
Still, the EU remains cautious about the direction of its second-largest trading partner, concerned by its militarisation of islands in the South China Sea and what it sees as increased authoritarianism under Xi.
EU officials say they will bring up the South China Sea in the talks on Friday, but they will be wary to avoid a repeat of last year's tense EU-China summit in Beijing, which failed to agree a joint statement because of the maritime issue.
China's claims in the South China Sea, through which about $5 trillion in ship-borne trade passes each year, are contested by Brunei, Malaysia, the Philippines, Taiwan and Vietnam.
The EU also wants an investment treaty with China to open the huge Chinese market to European companies and remove onerous rules forcing them to share know-how.
A senior Chinese official said China is determined to open up and reach a deal, which is seen as a forerunner to a possible future free-trade accord. (Additional reporting by Philip Blenkinsop, Stine Jacobsen in Olso, Madeline Chambers in Berlin and David Stanway in Beijing; Editing by Mark Heinrich, Larry King)
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