Clifford Chance (CC) and Cleary Gottlieb Steen & Hamilton have won key advisory roles on one of the world's biggest potential takeovers – Brazilian mining company Vale's approach to Swiss rival Xstrata for an estimated $90bn (£44.9bn).

If the deal goes ahead it would see Vale threatening BHP Billiton's position as the world's largest mining company. CC has won the lead role for Vale, with the magic circle firm fielding a team led by Sao Paulo-based relationship partner Anthony Oldfield and London-based corporate partner David Pudge.

US leader Cleary Gottlieb is providing the Brazilian company with competition advice on the deal, led by Brussels partners Nicholas Levy and Brian Byrne, along with counsel Christopher Cook.

With a formal bid still to be announced, Xstrata's advisers are yet to be confirmed. Freshfields Bruckhaus Deringer is the mining company's regular adviser – with London corporate partner Julian Makin responsible for the relationship.

The news comes as it emerges that Jones Day and Linklaters could also be in line for roles on a separate multibillion-pound mining deal – a potential merger of copper miner Kazakhmys with rival Kazakh mining group Eurasian Natural Resources Corporation (ENRC).

Jones Day is understood to be fielding a team for ENRC under London head Russell Carmedy, while Linklaters is thought to be advising Kazakhmys, which has so far denied any approach.

Kazakhmys has previously used a number of City firms including Allen & Overy, Linklaters and Norton Rose. Last year, Linklaters advised on its $801m (£400m) acquisition of an 18.8% stake in ENRC.

The deals are the latest examples of consolidation in the mining sector. Other recent deals include the Aluminium Corporation of China's (Chinalco) joint acquisition with Alcoa of a 12% stake in Rio Tinto for around $14bn (£7bn).