“We successfully defended a number of claims at an employment tribunal held in November 2007. “Miss Popa then failed in her attempt to secure an appeal to the Employment Appeals Tribunal.
She claims there was widespread discrimination against Romanians with many passed over for promotion and left to do mundane work.
Miss Popa has already taken the firm to an employment tribunal and lost, but claims this time to have more detailed evidence.
A spokeswoman for Pw C said: "Pw C LLP strenuously denies the allegations made by Miss Popa in relation to her employment with the firm from 2004 to 2006.
She now suffers from severe depression and anxiety and says her career as an accountant has been ruined.
She said: "They said originally that they thought I could be a future partner but then they never gave me the opportunity." She says her treatment, while employed at the firm between 20, became "progressively unbearable" until she felt she had no option but to resign.
Miss Popa, who lives in Hampstead, North London, started her career at Pw C's office in the Romanian capital Bucharest in 2000 where she won a scholarship to study for a Master's degree in finance at the University of Chicago.
She then worked briefly as an accountant in Pw C's Chicago branch, where she also claims she suffered racial discrimination, before transferring to London in September 2004.
Miss Popa also claims that during an office discussion about an outbreak of bird flu in Romania, one male member of staff pointed at her and said "this Romanian bird will have a slow death".
But a spokeswoman for Pw C dismissed the £40million figure as “without any merit” and said that her claims had already been dismissed by a previous employment tribunal.
She earned £41,000 a year as a forensic accountant for Pw C, but legal documents submitted to the Central London Employment tribunal show she is claiming £40 million in compensation for loss of earnings and illness – believed to be the highest amount ever to be claimed in a race discrimination dispute.
She says that she had been told by the firm she could be a future partner, earning at least £500,000 a year plus bonuses, which she will now miss out on.