Ministry sources told The Hindu that cost negotiations have been completed recently and the file would soon be sent to the Defence Ministry's finance wing.
From the finance wing, the file will go to the Finance Ministry before being put up for final approval before the Cabinet Committee on Security headed by the Prime Minister.In 2009, India signed a contract for eight P-8Is in a deal worth $ 2.2 billion from Boeing under a direct commercial deal with an optional clause for four more.
The Navy which is quite satisfied with the aircraft has decided to exercise the optional clause and negotiations have been going on for about a year.
Seven aircraft have already been inducted and are based in Arakkonam in Tamil Nadu. The last aircraft is expected to be delivered by October.
The P-8I is a next generation surveillance aircraft based on Boeing 737 commercial airliner and India is its first international customer. It is meant to replace the legacy of Russian aircraft currently in service. India had also purchased 26 Harpoon anti-ship missiles from the US to equip the P-8Is.
Two Boeing P-8I Neptune maritime patrol aircraft of the Indian Navy.