"It was Atal Ji's exemplary leadership that set the foundations for a strong, prosperous and inclusive India in the 21st century," current Prime Minister Modi said in a tweet Thursday, adding that the death of the politician became a "a personal and irreplaceable loss" for him.
The former prime minister was admitted to a hospital earlier in June due to kidney and bronchial problems and his condition has been on the decline ever since.
Vajpayee founded the Indian People's Party (BJP), and became its first president, making the party second powerful political force in the country. During his second term as Indian PM he also launched peace process with Pakistan a year after a nuclear weapons tests crisis in 1998. In 2014 he has received the most prestigious civilian Indian award, the Bharat Ratna.