Mumbai: Corus Steel, the world's sixth-largest steelmaker, has moved the European Commission against BHP Billiton's $208 billion bid to take over mining major Rio Tinto, even as reports said top producer AcelorMittal is planning to enter the race for Rio Tinto.

''Corus has stepped up its campaign against BHP Billiton's attempt to take over mining rival Rio Tinto by complaining to the European Commission about the deal," The Sunday Times reported.

The UK steelmaker, which was consulted by the EC about BHP-Rio, gave "very, very strong negative sentiments on further concentration in the iron ore industry," the newspaper quoted Corus CEO Philippe Varin as saying.

A Rio-BHP combine could control about 36 per cent of the world's seaborne trade in iron ore.

The Financial Times, meanwhile, quoted people close to the development as saying that Luxemburg-based ArcelorMittal was looking to enter the takeover battle for Rio Tinto.

Lakshmi Mittal, chairman and top shareholder of ArcelorMittal, is keen to secure larger supplies of iron ore.

Both Corus and ArcelorMittal are majority owned by Indian entrepreneurs - Ratan Tata and Lakshmi Mittal.

Australian mining group BHP Billiton had offered to acquire Rio Tinto, one of the world's major producers of iron ore, worth about $160 billion at its current market value, in a contested bid. BHP's $208 billion offer is being scrutinised by antitrust regulators.

"Mr Mittal has considered some involvement in the takeover, such as the idea of taking a stake in Rio through buying from existing shareholders," the newspaper quoted unnamed sources as saying. Alternatively ''he could also wait until later, when quite possibly some of the iron ore assets go on sale as a result of demands by antitrust regulators," the report added.

The Financial Times said bankers have assessed Rio's iron ore assets at around $50 billion, adding, this could fall sharply in the next few months, if demand for steel falls.

ArcelorMittal aims to raise own supplies of iron ore from the current 45 per cent to 70 per cent by 2012, to protect itself against surging raw material prices.

This would also boost its steel production 18 per cent to 130 million tonnes per year by 2012.

Prices of iron ore and coal have jumped in fiscal 2008-2009 amid strong demand for steel, impacting earnings of global steelmakers.