PARIS - The European Union (EU) is planning "a whole arsenal" of counter-measures if US President Donald Trump goes ahead with imposing new tariffs on imported steel and aluminum amid global opposition, an official said on Thursday.

"Donald Trump is wrong. All war is bad and in trade war there would be only losers ... The commission is preparing a riposte," European Financial Affairs Commissioner Pierre Moscovici told a French television news channel.

"If Donald Trump puts in place the measures this evening, we have a whole arsenal at our disposal," he said.

The former French economy minister said that "immediate" retaliatory measures would include European tariffs on US exported oranges, tobacco and bourbon, and goods which he said were mainly produced in constituencies held by Trump's Republican party.

Europe would also take measures to limit eventual excess of imported steel and aluminum into Europe in line with World Trade Organization (WTO) rules while filing a complaint before the WTO, he added.

Moscovici said Europe "wants to avoid escalation" but "must keep the multilateral framework" because "protectionism is never the answer: protectionism is nationalism, nationalism is war and the war only makes losers."

Trump announced on Thursday last week that the United States was set to impose a 25 percent tariff on steel imports and 10 percent on aluminum imports.

Trump is expected to sign the text on new duties later Thursday.