After three years of negotiations, the 28 nations voted to give Europe greater leeway to fight cheap imports of raw materials in a move that is sure to deepen a growing trade feud with China.
"This is a major breakthrough," said Peter Ziga, the trade minister from Slovakia, which holds the European Union's six-month rotating presidency.
"Europe cannot be naive and has to defend its interests, especially in case of dumping," he added.
Those fears have grown since the election of President-elect Donald Trump on a mandate to curb open international trade in the United States, the world's biggest economy.
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Steelmakers were especially keen for the changes after being battered by a collapse in prices due to China-led oversupply and a wave of cheap imports.
The measures agreed yesterday change the so-called "lesser duty rule", which strictly limits EU anti-dumping tariffs.
Under the existing system, the US can impose far harsher tariffs than the EU on Chinese steel imports.
"We are finally putting an end to this self-censorship," a European diplomat told AFP.
The breakthrough at the EU came a day after China began a legal challenge at the World Trade Organization over the reluctance by Brussels and Washington to treat Beijing as a "market economy".
When China joined the WTO in 2001 it was written into the terms of the deal that member states could treat it as a non-market economy for only 15 years.