Freshfields Bruckhaus Deringer, Linklaters and Herbert Smith Freehills have picked up key roles as Anheuser-Busch (AB) InBev, the world's largest brewer, are confirmed to have proposed a merger with rival SABMiller that would create a $275bn (£177bn) company.

SABMiller issued a statement last month saying it had been informed that AB InBev intended to make a bid proposal for the company.

Freshfields is advising AB InBev with a team comprising London M&A partner Mark Rawlinson, London head of corporate Simon Marchant and antitrust partner John Davies, who works out of London and Brussels.

Linklaters is advising SABMiller with a London team led by corporate partners Nick Rumsby and Charlie Jacobs. Brussels-based partner Gerwin Van Gerven is advising on competition issues. 

Herbert Smith Freehills (HSF) is advising BevCo Ltd, the second largest shareholder in SABMiller.

The HSF team is being led by London corporate partner Gillian Fairfield. Fairfield recently led the team advising British American Tobacco on its conditional agreement to acquire 100% of CHIC Group, Europe's largest e-cigarette retailing network.

Hogan Lovells is also acting alongside Linklaters for SABMiller, with a team led by London corporate partner Andrew Pearson. The exact remit of the firm's role is unclear.

AB InBev owns beer brands including Budweiser, Corona and Stella Artois, while SABMiller, which is headquartered in the UK, is home to brands such as Fosters, Grolsch, and Peroni.

A successful tie-up would rank as one of the largest corporate deals in history. Other recent mega-deals include Shell's £47bn acquisition of BG Group earlier this year and Vodafone's $130bn (£84bn) sale in 2013 of its 45% stake in US mobile operator Verizon Wireless.

In 2012, Freshfields advised AB InBev's on its $20bn (£12.8bn) acquisition of the Mexican brewer behind brands including Corona and Grupo Modelo alongside Skadden Arps Slate Meagher & Flom and Sullivan & Cromwell.

Linklaters, meanwhile, is understood to have advised SABMiller last year on its failed efforts to buy Heineken, one of Europe's largest breweries.

SABMiller saw its takeover for Heineken rejected in September, with the Dutch company calling the approach "non-actionable" and insisting it wanted to maintain its independence. A&O advised Heineken after previously taking a role for SABMiller when the brewer launched a successful A$11.5 billion (£7.8bn) takeover of Fosters three years ago.

Reports have suggested that SABMiller launched its Heineken takeover bid in order to safeguard itself against an approach from AB InBev.

Clifford Chance is advising the controlling shareholders of AB InBev with a team led by global head of corporate Guy Norman and London corporate partner Patrick Sarch. The firm is also advising the company on the financing of the transaction with a team led by finance partners Roderick McGillivray and Peter Dahlen in London