The Indian-British businessman Sanjeev Gupta has described how companies within his steel conglomerate used stamps and digital images of his signature to certify documents because it was “simply not physically possible” for him to attend to the business personally and that the practice meant his signature was on documents he “had not personally reviewed or ever seen”.

Gupta’s legal representatives have made the statement in a defence document submitted as part of a $400 million dispute between Greensill, the collapsed financial firm, and Zurich, its insurer.

Zurich is arguing it does not need to pay out on insurance policies agreed with Greensill’s defunct German banking unit because its underwriters were deceived into providing coverage for an alleged “fraudulent scheme”. Zurich has claimed that Gupta and Lex Greensill, the founder of Greensill, conspired to mislead its underwriters.

Greensill prompted a political scandal when it fell into administration in March 2021 because the insolvency revealed that Lord Cameron of Chipping Norton, the former prime minister, had lobbied government officials to secure contracts for the firm. Greensill’s collapse has prompted a number of legal cases as creditors seek their share of funding from its insolvent estate.

Gupta, 52, and Lex Greensill, 47, have issued their defences to Zurich’s claims in the High Court, with Greensill stating he was “not party to the alleged or any fraudulent scheme” and that “he did not fraudulently or recklessly withhold information from Zurich”.

Zurich has alleged Gupta was “heavily involved” in a scheme because he spoke to Lex Greensill “generally on a daily basis”. It has said there was “no valid transaction” under the agreement with Gupta because he had not signed the document personally.

Gupta’s legal representatives have said he often did not personally sign the documents because his company used stamps bearing his signature to provide certification, before moving on to using a digital image of his signature when “technology improved”. The documents state that Gupta “relied on what was said between him and Mr Greensill, rather than the terms of the contractual documents” and that he “understood those arrangements constituted legitimate and genuine financing”.

The document states: “Given the large number of companies of which Mr Gupta was an officer and/or in which he held a commercial interest, across the globe, there was a large number of documents which required Mr Gupta’s signature from time to time, and it was simply not physically possible for Mr Gupta to sign all of the documents on which his signature was sought.

“A practice evolved such that where a document may appear to have been signed by Mr Gupta, it in fact bears a stamp signature or a digital impact of his signature, and may be a document which Mr Gupta had not personally reviewed or ever seen.”

Zurich has alleged that Lex Greensill made companies he controlled advance loans tocompanies withinGupta’s steel conglomerate backed by payments that “did not exist” from a list of suppliers. The insurer alleges that Greensill and Gupta both made statements proving its case that “there were no genuine accounts receivable” owed to the company within the magnate’s GFG Alliance group. Gupta and Greensill have both denied making the admissions.

In court documents, Zurich said Gupta had outlined how Greensill would advance finance based on companies “with whom its counterparties could potentially do business in the future” and determined the amount of possible business “at its discretion”. Lex Greensill has claimed that he understood all finance provided to Liberty Commodities, the company at the centre of Zurich’s case, was advanced on the basis of amounts already owed by third parties, rather than amounts that could be created by new business in the future. He has said that if sums had been advanced on other terms, then “he was misled by Mr Gupta, the GFG companies, or both”.

Greensill’s document states: “Mr Greensill was not part of the alleged or any conspiracy, whether with Mr Gupta or others.”

A GFG Alliance spokesman said: “GFG Alliance was not involved in any insurance arrangements which Greensill had in place and any attempt to link us to the Greensill insurance is misplaced.”

A spokesman for Lex Greensill declined to comment.