Quinn Emanuel Urquhart & Sullivan has taken the lead role for private equity firm PCP Capital Partners on its dispute with Barclays over a controversial $3bn capital-raising exercise by the bank at the height of the 2008 financial crisis.

The US litigation firm has taken over from City firm Fladgate, which was previously advising PCP with a team led by white-collar crime partner Bree Taylor.

Quinn London managing partner Richard East is heading up his firm's team now advising PCP, while Simmons & Simmons is acting for Barclays with a team led by London senior partner Colin Passmore.

The dispute dates back to 2008, when Barclays was looking to raise billions of pounds in capital and was in discussions with both PCP and Qatar Holding, then the bank's largest shareholder.

PCP was working with Sheikh Mansour, a member of the ruling family of Abu Dhabi, on a deal to join the syndicate of investors in Barclays.

In a claim filed this August in the Commercial Court in London, PCP alleges that Barclays acted dishonestly with regards to the different terms offered to Qatar Holding and PCP for participation in the capital raising.

The private equity vehicle claims that its reliance on Barclays' representations meant that it missed out on a windfall in potential fees or profits, and is claiming hundreds of millions of pounds in damages.

Allen & Overy took the lead role for PCP in 2008, while Clifford Chance acted for Barclays.

The court filing also claims that Linklaters pulled out of representing Barclays in 2008 because of concerns over the legality of the Qatar loan.

It states that Linklaters told Latham & Watkins, which was acting for the State of Qatar on the proposed loan, that "[so as to] seek to ensure that no financial assistance is being provided… the purpose clause should make it clear that the facility is being used for investments other than in Barclays".

It continues: "The Qatar Facility Agreement did not include any such representation," and "on the same day or the next, Linklaters declined to continue to act for Barclays in respect of the loan… It should be inferred that Linklaters resigned (at least in part) because it was concerned that the Qatar loan would be illegal, specifically that it would involve unlawful financial assistance by Barclays for the purchase of its own shares."

This June, it was revealed that Barclays and four of its former executives are facing fraud charges over the 2008 Qatari loan. The Serious Fraud Office announced that Barclays and the four individuals had been charged with "conspiracy to commit fraud and the provision of unlawful financial assistance".