Slaughter and May billed Carillion £8.4m for advice in the 18 months prior to its liquidation in January this year, a newly-released letter from the firm has revealed.

The figure is revealed in a letter from Slaughters senior partner Steve Cooke, sent to MPs after the magic circle firm was asked in February to provide information to the Work and Pensions and Business, Energy and Industrial Strategy committees, which launched a joint inquiry into Carillion's liquidation at the beginning of 2018.

The letter, dated 20 February but only released this week after the publication of a final report into the construction company's high-profile collapse, states that Slaughters racked up fees of £8.387m for work carried out between July 2016 and January 2018, of which £6.894m has been paid.

The letter, which states that a further £1.2m was unbilled, adds that "in the leadup to and following" Carillion's July 2017 profit warning, which saw shares crash 40%, the firm billed £6.915m, of which £5.468m was paid. This figure includes fees for advice on a rights issue that the firm started working on in May 2017.

The letter states that the fees do not include disbursements or VAT, and adds that the firm was not paid any success fees. Cooke wrote: "Had our work relating to Carillion's financial position concluded, we would have then had the ability to seek an uplift on our fees."

The publication of the letter comes after MPs published a critical report this week on Carillion's collapse. Slaughters, Freshfields Bruckhaus Deringer and Clifford Chance were among the law firms accused by MPs of "squeezing fee income" from the company as it collapsed amid "recklessness, hubris and greed".

The report, released on Wednesday (16 May), details how Carillion's directors were supported by an "array of illustrious advisory firms" which, as it unravelled, were "squeezing fee income out of what remained of the company".