The 500-million-dollar deal announced in February would see two ferronickel-producing sites in Brazil and two additional projects in the country be taken over by MMG, whose largest shareholder is a Chinese state-owned company.

In a statement, the European Commission said the deal could allow MMG to restrict the supply of ferronickel -- a key alloy used in stainless steel production -- to European steelmakers, potentially driving up their manufacturing costs.

MMG has already submitted commitments to address the Commission's concerns, but Brussels deemed them insufficient at this stage.

As a result, the EU executive has opted to open a full-scale investigation, to be concluded by March 20 next year.

An Anglo American spokesperson told AFP that the company "does not believe this transaction presents competition concerns" for Europe and said it was "fully committed" to seeing the deal through.

Anglo American will continue to work with the European Commission to "progress the approval process and comprehensively address any outstanding questions", the spokesperson added.

Founded in 1917 in South Africa by German-born industrialist Ernest Oppenheimer, Anglo American is one of the world's largest mining companies, listed in both London -- where it is headquartered -- and Johannesburg.

The group is currently undergoing a transformation, with plans to divest from several business units such as metallurgical coal, platinum and diamonds in South Africa in order to refocus on copper, premium iron ore and fertilisers.