Rolls-Royce allegedly paid millions of pounds in bribes to land major contracts around the world.
The claim was made by BBC's Panorama, alleging that the iconic British company paid over £10m to a network of unregistered agents in order to land contracts in up to 12 countries. The agents are now the focus of investigations by anti-corruption agencies in the UK and the US.
Panorama reported that the UK-based firm paid money to companies linked to Indian arms dealer, Sudhir Choudhrie, which may have helped the company win a major contract for engines on Hawk aircraft, to be purchased by an Indian state-controlled company.
It is illegal to pay secret middlemen to win defence contracts in India and Choudhrie is also on a government blacklist in the country, an Undesirable Contact Men list, containing people suspected of "corrupt or irregular practice".
Rolls-Royce have said they have zero tolerance towards bribery and corruption and Choudhrie's lawyers said he "has never paid bribes to government officials or acted as an illegal middleman in defence deals".
Billionaire Choudhrie and his family run multiple global businesses and he is an adviser on India to the Liberal Democrat leader Tim Farron having donated more than £1.6m to the party.
The BBC programme, in conjunction with The Guardian newspaper, identified one payment they allege was between Choudhrie's son, Bhanu, and an arms executive called Peter Ginger in Switzerland in 2007.
They allege Ginger made a cash payment amounting to hundreds of thousands of pounds into a secret bank account in the name of "Portsmouth" which had a balance of more than 1m Swiss francs, according to documents the BBC says it has seen.
They also claim that Ginger was a key negotiator on the sale of Hawk aircraft to the Indian government which all had Rolls-Royce engines in a deal worth around £400m.
Bhanu Choudhrie's lawyers in response to the allegations that: "Mr Choudhrie has never paid any bribe to Mr Ginger or anyone else," his lawyers said. "Mr Choudhrie has no knowledge of what bank accounts have been set up or operated by Mr Ginger or what sums (if any) he has deposited in them in cash."
Ginger said he has never acted for Rolls-Royce, or had any financial dealings with them, and has never taken or received bribes. It is understood that in 2014, Sudhir and Bhanu were arrested as part of the Serious Fraud Office (SFO) investigation into Rolls-Royce, with the pair released without charge.
The BBC also reported that Brazil-based Pedro Barusco, a Petrobras executive, allegedly received illegal payments linked to Rolls-Royce. In official documents he is said to have told prosecutors that payments from the company totalled $200,000 (£163,000).
Rolls-Royce employs 23,000 people in the UK selling turbines and engines for passenger jets and military aircraft and is worth an estimated £13bn.
Rolls-Royce said: "We have made it clear that Rolls-Royce will not tolerate business misconduct or inappropriate behaviour of any kind and in recent years we have intensified our focus on ethics and compliance, which are foundations of our culture."