Allen & Overy (A&O) and Skadden Arps Slate Meagher & Flom have won the lead mandates on Shell's $1bn (£617m) sale of parts of its African business.

The deal, which comes as Shell moves to sell off non-core operations, will see oil trader Vitol and private equity firm Helios Investment Partners acquire the majority of Shell's shareholdings in its downstream businesses in Africa.

A&O advised Shell with a City team led by corporate partner Dominic Morris alongside corporate partner Gillian Holgate and senior associate David Duncan. Banking partner Philip Bowden also advised on financing.

Skadden represented Vitol and Helios, with City energy partner Doug Nordlinger leading the US firm's team, which also included partners Shaun Lascelles, Tim Sanders, Chris Baker, Mark Darley, Clive Wells and counsel Scott Brown.

Dutch firm De Brauw Blackstone Westbroek also advised Vitol and Helios with a team led by partner Ernest Meyer Swantee.

The deal will see two new joint venture companies formed which will continue to sell fuels and lubricants in 14 African countries under the Shell brand.

One joint venture will own and operate Shell's existing oil products, distribution and retailing businesses in 14 African countries, with the potential to add five more in future. Vitol and Helios will hold 80% of the venture and Shell will hold the remaining 20%.

A separate company, 50% owned by Shell and 50% by Vitol and Helios, will own and operate Shell's existing lubricants blending plants in seven countries and will manage macro-distributor relationships in each of the countries where the main venture operates, plus a number of others.

The complex deal, which is pending regulatory approval and integration planning, is expected to be completed by the first half of 2012.

Shell completed a panel review last year which saw Clifford Chance and A&O appointed as the energy giant's main M&A legal advisers.