Slaughter and May, Jones Day and Cleary Gottlieb Steen & Hamilton have secured lead roles on BHP Billiton's $40bn (£25.6bn) hostile bid for the Potash Corporation of Saskatchewan, writes the Am Law Daily.

Potash rejected the mining giant's unsolicited offer on Tuesday (17 August), with BHP today (18 August) confirming a hostile bid at $130 (£83) a share for the Canadian-based company, which is the world's largest producer of fertiliser.

Slaughters, Cleary and Canadian firm Blake Cassels & Graydon are advising BHP. The Slaughters team advising on English law aspects of the offer includes partners Andrew Balfour, Philip Snell and Richard de Carle.

The deal has also handed a role to Allen & Overy, which advised the banks on a $45bn (£29bn) loan facility supporting the BHP bid. The magic circle firm floated a team including City banking partners Nick Clark and David Murray, Sydney-based banking partner Chris Robertson as well as New York-based finance and restructuring partner Elizabeth Leckie and senior banking counsel Jacob Minas.

Meanwhile, Jones Day M&A partners Robert Profusek in New York and Philip Stamatakos in Chicago are leading a team advising Potash. Other Jones Day lawyers involved in the effort include M&A partner Christopher Hewitt, corporate partner Edward Winslow, and antitrust partners Michael Sennett and Tom Smith.

Jones Day has previously represented Potash on the company's issuance of $1bn (£641m) in senior notes, antitrust litigation, aircraft purchases, and the development of nitrogen fertiliser complexes in the Middle East and North Africa.

William Braithwaite, a senior partner and former head of the corporate group at Canadian law firm Stikeman Elliott in Toronto, is also advising the Saskatoon-based Potash along with M&A partner John Ciardullo, antitrust partner Susan Hutton, and regulatory counsel Lawson Hunter. The firm has previously represented Potash on several matters, most of them transactional.

Potash's rejection of the BHP offer comes three days after the Australian mining giant made its initial unsolicited bid.

It is expected that Canadian takeover rules will weigh heavily on any potential transaction. BHP's bid for Potash is based on a bet on the world's increasing demand for food, in particular for more meat from emerging economies.

The Am Law Daily is an affiliated US title of Legal Week.