Macfarlanes and Slaughter and May have taken central roles in the proposed takeover of the Hilton Group by its US arm, Hilton Hotels Corporation (HHC), which could be worth up to £3.6bn.

Macfarlanes is working with HHC for the first time, advising on UK law for the company. It is understood that this instruction came through the firm's referral links in the US.

The deal is the latest in a line of top-tier transactions for the mid-tier firm, which earlier this year also advised Pernod Ricard on its £7bn takeover of drinks rival Allied Domecq.

Corporate partner Charles Martin is leading the team advising HHC, assisted by fellow partners Matthew Blows (corporate), Clive Lampard (property) and Hugh Arthur (pensions).

Slaughter and May is advising long-term client Hilton Group, which is headquartered in the UK and owns Hilton International – the operator of more than 400 hotels around the world. The UK hotel chain announced it had received an indicative offer from HHC on 14 October but has not disclosed a value.

Corporate partners Richard de Carle and Padraig Cronin are leading the Slaughters team, which includes real estate partners David Beales and Graham White. Finance partners Richard Levitt and Andrew Balfour are also advising.

Both companies have also instructed US counsel on the talks, with HHC turning to New York powerhouse Sullivan & Cromwell and Hilton Group instructing Simpson Thacher & Bartlett.

Sullivan corporate partners Alison Ressler in Los Angeles and Richard Morrissey in London are leading the team advising HHC, with London corporate partner Robert Schlein and tax partner Andrew Solomon also advising. It is the first deal Sullivan has acted on for the client, although it has had links to the company since 2001.

London corporate partner Michael Wolfson is leading the Simpson Thacher team advising Hilton Group.

Jackie Newstead, a property partner at Lovells, said: "This is a major event. The effect it has on Hilton's other businesses, such as the casinos and gaming side with Ladbrokes will be significant. It will also be interesting to see what happens to the smaller deals Hilton International was working on."