Orsi’s appointment to lead the defence group in May 2011 was backed by the Northern League party, at the time an ally of then Prime Minister Silvio Berlusconi.
Center-left politicians had called for Orsi to step down when he was first targeted in the corruption probe. Orsi, a long-serving defence industry executive, has denied wrongdoing.
Shares in the group fell 11% by 0846 GMT in Milan, while its rail technology unit Ansaldo STS was down 3.5% after earlier being suspended because of losses.
The Indian foreign ministry said Italy had not shared details of the corruption probe into the helicopter sales. India’s defence ministry said it could not immediately comment.
The first helicopters, for use by India’s political leaders, were due to be delivered by December 2012 after a 560 million euro ($749.2 million) contract was awarded in 2010.
The source said three other people had been placed under house arrest as part of the probe, including the chief executive of AgustaWestland, Bruno Spagnolini.
Orsi, CEO at Finmeccanica since 2011, has been steering the loss-making company through a restructuring. Finmeccanica, around 30% owned by the Italian state, has said it has always done business in India through official channels.