Accountancy firm KPMG has quit its advisor role on the Grenfell inquiry amid concerns over its appointment.
Campaigners had called for KPMG to be removed, saying it failed to disclose a conflict of interest.
KPMG is the auditor of three of the firms under scrutiny by the inquiry into the tower block blaze, in which 71 people died on 14 June last year.
The firm said it had "mutually agreed with the inquiry that we will step down from our role with immediate effect".
The accountancy firm audits the Royal Borough of Kensington and Chelsea, where the tower is located.
It also audits Rydon Construction, which refurbished the tower in 2015, and Celotex, which manufactured insulation material used in the tower.
Pop star Lily Allen, two Labour MPs - Clive Lewis and Emma Dent-Coad - and a host of academics and campaigners had earlier signed an open letter to Theresa May urging the prime minster to reverse KPMG's appointment.
They said the appointment would "only further fuel rumours of a deliberate cover-up and erode public trust."
KPMG said its role on the inquiry as project management advisor was "purely operational" and that it had no role advising "on the substance of the inquiry".
"Whilst we are confident that no conflicts exist between our role advising the inquiry and our work for other clients, we recognise that strength of opinion about our role risks undermining confidence in the Inquiry," a spokesperson added.
The firm said it would waive its fees for the work undertaken to date.
Last month, survivors and bereaved families warned the Grenfell Tower fire inquiry could become a whitewash unless a diverse panel was appointed to oversee proceedings.
Sir Martin Moore-Bick's appointment as the inquiry chairman has already been criticised by residents, who say he is an establishment figure.
Victims groups were further angered when the retired Court of Appeal judge said he would not appoint a member of the Grenfell community to the panel, arguing it would "risk undermining impartiality".