The Central Bureau of Investigation (CBI) is likely to question Andhra Pradesh Governor ESL Narasimhan on Wednesday as part of its investigation into the bribery scam.
Governors of West Bengal and Goa had resigned after the CBI interrogated them as witnesses.
The deal for the helicopters was cancelled by India in 2013.
Narasimhan was the head of the Intelligence Bureau in 2005 when Indian twisted the technical specifications for the helicopters it wanted to procure.
Meanwhile, widening its probe into money laundering charges in the Rs 3,600-crore VVIP chopper deal, the Enforcement Directorate would send judicial requests to about six countries seeking information on bank accounts and transactions to detect the trail of alleged kickbacks money.
The agency, which filed a criminal case two days ago under the provisions of the Prevention of Money Laundering Act (PMLA) in the deal which was cancelled last year by the government, has detected that over 170 'fake firms" were floated to route the alleged illegal funds between Indian and foreign firms.
The agency is expected to send Letters Rogatory (judicial requests) to Italy, Mauritius, the UK, Tunisia, Dubai and few other jurisdictions in Europe to piece together the flow of funds and money in this deal, sources said.
The ED, the sources said, would make these requests under the existing protocols and tax information exchange treaties between India and these jurisdictions as defined for assistance in criminal matters.
The agency had earlier registered a case under foreign exchange laws in this deal after which it decided to lodge a criminal case under PMLA to trace the bribe money involving middlemen and other people named by CBI in its FIR filed in March 2013.
Taking cognisance of the more-than-a-year-old CBI complaint, the agency has booked former IAF chief S P Tyagi, his family members, European nationals Carlo Gerosa, Christian Michel and Guido Haschke, four companies-- Italy-based Finmeccanica, UK-based AgustaWestland and Chandigarh-based IDS Infotech and Aeromatrix, two companies based in Mauritius and Tunisia, few other firms and unknown persons in its criminal complaint.
A total of 21 entities have been named by ED in the case. (PTI)