Finally, the kickbacks were to the tune of about Rs 362 crore.
The payment of bribes through contracts between firms registered in Tunisia and India, was "still underway" when the scam was unearthed.
The report said CEO of Finmeccanica Giuseppe Orsi and AgustaWestland CEO Bruno Spagnolini had paid 30 million Euros (Rs 217 crore) to one of the main middlemen Christian Michel.
"Orsi and Spagnolin, moreover, paid Micheal Christian a total amount of about Euros 30 million, partly destined to support the corruptive activity meant to bag the order and partly to implement the contract," the document said.
The arrested CEOs of the two companies had also "paid Guido Ralph Hashcke and Carlo Gerosa (two other alleged middlemen), through a consultancy contract between AW spa and Gordian Services Sarl an amount of 400,000 Euros (about Rs 2.8 crore), of which 100,000 Euros (Rs 72 lakh) were paid cash to the Tyagi brothers (Julie, Docsa and Sandeep."
The report suggests that the middlemen had close contacts with the family of former IAF Chief Air Chief marshal S P Tyagi, particularly his three cousins.
One middlemen named 'ADR' has claimed in his interrogation that the first meeting of one of the middlemen Zappa with Tyagi happened at the time when the tender was in the Request for Information (RFI) phase.
"Already in the Zappa-ACM Tyagi meeting, one of the topics was the one of the 18,000 feet altitude, which was practically excluding all the competitors, except for the French ones, Eurocopter which anyway did not have a VIP model," ADR said as per the report.
"When the tender was issued, I informed Orsi or Lunardi that the 18,000 feet limit had been lowered. The operational ceiling had been set at 15,000 feet. This had reopened the race for Agusta along with the Russians and the Americans," he added.
The middleman reportedly claimed he had paid around Rs 72 lakhs to the three cousins of ACM Tyagi.
"I remitted the total amount of 100,000 euros (Rs 72 lakhs). There was a previous agreement between us and the Indians to share the compensations for the consultancies at 50%.
"In reality, we shared only the first two portions. The other 200.000 euros were kept by me and GEROSA also on the basis of the real expenses we faced for our travels to India," he said.
The middleman alleged that Tyagi used to brief them about the developments in the tender during their meetings, according to the report of the Italian investigators.
The report said "Haschke and Gerosa, through the Tyagi brothers, in turn through their cousin ACM S P Tyagi, managed first to change the tender details, in a way to favour, modifying the 'operational ceiling' from 18,000 to 15,000 feet of altitude, thus allowing AgustaWestland spa (which otherwise could not have even submitted an offer) to take part in the tender."
"They managed to introduce a comparative flight trial with non-functional engine, thus facilitating AgustaWestland helicopters, the only ones which had three engines. In this way they managed to get the contract to AgustaWestland," it alleged.
After the arrest of Orsi and Spagnolini in Italy, India has put on hold the delivery of three AW-101 choppers to be delivered in March along with the remaining six.
The payments for the choppers has also been stopped and defence ministry has stated that because of the integrity pact, it can get back all the money paid by it for the deal.