Addleshaw Goddard has received around £50m in fees from its representation of Boris Berezovsky over the last four years, as details of the Russian oligarch's £20m fees to the Bar have also emerged.

The UK top 20 law firm has generated total fee income of £50m since taking on the mandate in January 2009, including a £15m success fee relating to Berezovsky's recent settlement with the family of now-deceased Georgian billionaire, Arkady 'Badri' Patarkatsishvili.

The dispute centred around whether Berezovsky had an interest in certain assets held by Patarkatsishvili after he died in February 2008.

The exact remaining breakdown of Addleshaws' fees is unclear; however, the firm's conditional fee agreement (CFA) with Berezovsky meant it agreed to act on a 50% fee basis for all of the work, with an 100% uplift if successful, doubling the firm's hourly rate in the case of a win.

In addition to advising Berezovsky in relation to his loss against Roman Abramovich, Addleshaws' mandate also covered action against Russian metal magnate Vasily Anisimov and investment company Salford Capital Partners, with the first action dropped and the second settling earlier this month.

Meanwhile, the majority of Berezovsky's Bar spend went in fees to Brick Court, One Essex Court and Fountain Court chambers.

Brick Court's Mark Hapgood QC, who was instructed to act for Berezovsky on his $3bn (£1.9bn) claim against the Patarkatsishvili family, received a brief fee of around £2m, of which he is understood to have received the majority, despite the case settling before trial.

One Essex Court's Laurence Rabinowitz QC, who led on the Abramovich proceedings, was handed a brief fee of £1.75m, while his counterpart, former Brick Court silk Jonathan Sumption QC – now Supreme Court justice, took a brief fee of £8m for his role acting for Abramovich.

Hapgood was brought in to represent Berezovsky after Rabinowitz opted to come off the case because of other commitments.

News of Addleshaws' fees comes after Berezovsky agreed to pay £35m of Abramovich's £40m legal costs last week following his high-profile litigation defeat to the Chelsea FC owner earlier this year. Berezovsky and Abramovich ended their $6bn (£3.8bn) litigation in August this year.

Addleshaws litigation partners Mark Hastings and John Kelleher led the firm's team for Berezovsky, working alongside Rabinowitz.

Berezovsky had claimed he was coerced by Abramovich to sell his stake in Russian oil company Sibneft at a significant undervalue, and that Abramovich sold his shares in Russian aluminium company Rusal without his consent.

Sumption acted for Abramovich alongside Skadden Arps Slate Meagher & Flom litigation partner Karyl Nairn, international arbitration partner Paul Mitchard QC and of counsel Rory McAlpine.

Hastings said: "The terms of the settlement are confidential between the parties. The details of the [fee agreement] with Mr Berezovsky or how much we may or may not receive are also confidential."

The news comes after much speculation that Addleshaws had made a loss from the case in light of its CFA deal and Berezovsky's court defeat to Abramovich.

Related: