Sir Philip Green has instructed media specialist Schillings to act for him regarding "highly defamatory and completely false" statements made by chair of the Work and Pensions Select Committee, Frank Field.

Following comments made by Field during yesterday's Radio 4 Today programme, Schillings has written to the Labour MP to demand "an immediate apology".

During the programme, Field, who co-led the Parliamentary inquiry into the sale and subsequent collapse of BHS, described Green as "worse than Robert Maxwell" – the disgraced ex-head of the Mirror Group who stole millions from its pension fund.

The letter from Schillings stated: "Our client requires an immediate and fulsome apology in relation to the allegation."

It added: "Clearly an allegation that our client is a thief is likely to cause him serious harm."

It said: "The other remedies to which our client is clearly entitled will very much depend on [the] form and manner of your response."

Green and Field have locked horns in the past few months, during the parliamentary inquiry into the sale and subsequent collapse of BHS, which left the company with a £571m pension deficit.

Field co-led the inquiry, which also pushed several law firms into the spotlight.

Linklaters, Olswang, Nabarro and Eversheds partners all appeared in front of the panel to give evidence.

Following the appearance of partners from Linklaters and Nabarro at a panel session on 23 May, Field spoke to Legal Week and expressed his frustration at what he saw as a lack of detail in the partners' responses to questions.

Field said: "I just think it's too easy to claim privilege. It's just laziness and a cover-up."

Yesterday, Olswang and Linklaters were criticised in the Select Committee's final report into the sale of BHS.

The report found fault with the "cursory nature" of the firms' checks into Dominic Chappell, the bankrupt and director of Retail Acquisitions Limited (RAL), which took over BHS last year prior to its collapse.

The report, released yesterday (25 July), states that firms were there to advise and "not to provide an expensive badge of legitimacy to people who would otherwise be bereft of credibility", which it says is what had happened.

The report adds: "In the case of BHS, it appears that advisory firms either did not consider the reputational risk or demonstrated a remarkable level of 'group-think' in relying solely on each other's presence."

Olswang and Linklaters decline to comment.