Two Governors - MK Narayanan of West Bengal and BV Wanchoo of Goa - have resigned after they were interrogated last week as witnesses by the CBI.
The deal for the helicopters, struck in 2010, was cancelled by India last year.
Mr Narasimhan was the head of the Intelligence Bureau in 2005 when India tweaked the technical specifications for the helicopters it wanted to buy, allowing AgustaWestland to qualify. Mr Narayanan was National Security Advisor at the time and Mr Wanchoo was head of the Special Protection Guard or SPG, which handles security for VVIPs.
Finmeccanica's then chief executive was arrested in February last year for allegedly paying bribes to secure the deal, embarrassing the government led by Dr Manmohan Singh, and triggering a CBI investigation.
The CBI alleges that bribes were paid, among others, to former Indian Air Force Chief SP Tyagi, to have that changed.
The retired Air Force chief has denied any wrongdoing. So has AgustaWestland and its parent company, Italian defence giant Finmeccanica.
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