India will purchase Russia's most advanced air defence system, the Kremlin said on Thursday.
"An agreement on the delivery of S-400 'Triumph' anti-missile defence systems and other deals will be signed as a result of the talks," Russian news agencies quoted Putin's aide Yuri Ushakov as saying, AFP reported.
The Indian defence ministry said New Delhi will purchase five S-400 air defence system.
Sources in the ministry said the deal would cost $4.47 billion, Reuters reported.
The S-400 system is a surface-to-air missile (SAM). The system can track some 300 targets and shoot down around three dozen simultaneously over a range of several hundred kilometres.
The countries will sign the deal when Russian President Vladimir Putin visits India for the BRICS Summit in India's western state of Goa on Saturday.
Putin is expected to meet Indian Prime Minister Narendra Modi on the sidelines of the international meet involving leaders of Brazil, Russia, India, China and South Africa.
India had initially planned to purchase 12 units, but later revised its order to five.
An agreement to build frigates for the Indian Navy would also be signed on Saturday, as well as a deal to set up a joint venture in India to build multi-task Kamov-226 helicopters, he said.