The Lehman Brothers liquidator has upped its claims against Barclays in the US, the Financial Times reports.

A new filing says the UK bank owes $11 billion from its acquisition of Lehman’s US operations after the September 2008 bankruptcy. First time round, the demand was for $8.2 billion.

It is alleged Barclays “studiously avoids the critical and inescapable fact that this court was not told about billions of dollars in unauthorised and undisclosed changes to the sale transaction it actually approved. When correctly valued, the assets Barclays acquired (or claims to have acquired) exceed the consideration Barclays actually paid by over $11 billion".

Barclays said: “More than a year after the terms were agreed upon and contrary to well-established federal law, the creditors seek to change the terms of the sale. Renegotiating the transaction would undermine the ability of the federal government and private parties in the future to sell distressed bank assets in order to protect as much as possible depositors, shareholders, creditors, and the government.”