Christian Michel James is accused of arranging kickbacks to Indian officials to secure a deal for AgustaWestland to supply New Delhi with 12 helicopters for 556 million euros ($630 million) in 2010.

Brought in from the United Arab Emirates late Tuesday, James appeared in a Delhi court amid tight security.

He will remain in police custody initially for five days and be allowed to meet his lawyer for one hour twice a day during this period, lawyers said.

Italian prosecutors suspect illegal sweeteners worth about 10 percent of the contract, or some 55 million euros, were paid out in bribes. India cancelled the deal in January 2014.

James, who in previous interviews with Indian newspapers denied any wrongdoing, was detained in Dubai in February 2017 following an Indian arrest warrant and an Interpol notice.

Indian Prime Minister Narendra Modi's Bharatiya Janata Party (BJP) has sought to capitalise politically on the scandal as the contract was signed under the previous government of the Congress party.

Addressing a rally in the northwestern state of Rajasthan on Wednesday, Modi said: "We have brought back the middleman. He will spill the beans."

The BJP said on Tuesday that the case could spell "serious trouble" for the "first family" of Congress, referring to the party's long-powerful Nehru-Gandhi dynasty, Indian media reported.

The Congress party had earlier alleged that the BJP government managed to force James to sign a false confession naming its former party chief Sonia Gandhi in exchange of exoneration from any charges.

In Italy, the former head of AgustaWestland and of parent company Finmeccanica were given jail sentences in 2014 over the scandal but they were later acquitted.