Representatives of the defunct Lehman Brothers estate have asked a US judge to reopen the contract that transferred the bank’s North American assets to Barclays Capital a year ago, claiming that up to $8bn in cash and securities was transferred to BarCap without the court’s knowledge.

Attorneys for Alvarez & Marsal, the turnround company hired by Lehman’s creditors to maximise the amount of recoverable assets, claimed that in the frenzied week during which Lehman’s US assets were sold to Barclays last year – for $1.75bn – the bankruptcy court was kept in the dark as to the true value of assets being transferred.