France, June 4 -- The European Union has said it "strongly regrets" a fresh move by US president Donald Trump to double import tariffs on steel and aluminium to 50 percent, warning the decision risks derailing efforts to resolve an escalating trade dispute with the United States. The new tariffs took effect on Wednesday.

Trump signed the order on Tuesday evening, raising the import taxes from the 25 percent rate first introduced in March. The metals sector was the first to face these targeted tariffs, part of Trump's stated aim to boost domestic investment.

The European Commission said the bloc was ready to respond if needed. A €21 billion package of counter-tariffs, approved earlier this year, remains on standby.

Italy's PM Melo...