UPDATE 1-EU antitrust regulators to investigate ArcelorMittal, Ilva deal

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BRUSSELS, Nov 8 (Reuters) - EU antitrust regulators opened a full-scale investigation on Wednesday into ArcelorMittal's proposed purchase of Italian steel plant Ilva, ratcheting up the pressure on the Luxembourg-based steelmaker to offer more concessions to address competition concerns.

The world's largest steelmaker reached a 1.8-billion-euro ($2.1 billion) deal to acquire Europe's biggest capacity steel plant in June. The loss-making plant in the southern Italian city of Taranto is grappling with a serious pollution issue.

The European Commission said it was concerned the merger may reduce competition in some flat carbon steel products and result in higher prices, especially for customers in southern Europe.

"Those European industries need access to steel at competitive prices to compete in global markets," European Competition Commissioner Margrethe Vestager said in a statement.

The Commission said concessions offered by ArcelorMittal last month failed to address its concerns, without providing details about the proposals. It will rule by March 23 whether to clear or block the deal.

Italian authorities are keen to keep the deal to save more than 10,000 jobs ahead of general elections due early next year.

($1 = 0.8628 euros) (Reporting by Foo Yun Chee; Editing by Francesco Guarascio and Mark Poter)