There has been angry reaction within India's governing Congress party to claims the KGB infiltrated Indira Gandhi's government in the 1970s.
Indira Gandhi sought stronger links with the Soviet Union
A former KBG official says in a new book that the Soviet intelligence agency had an extensive network of contacts in the government.
Congress party spokesmen say the allegations in the book are baseless and not worth commenting on.
Mrs Gandhi led three Congress governments before being assassinated.
Excerpts of the new book, The Mitrokhin Archive II: The KGB and the World, were widely published in the Indian press on Sunday.
In the book, ex-KGB worker Vasili Mitrokhin says the intelligence agency bribed Indian officials with millions of dollars, and used agents to persuade Mrs Gandhi to declare a state of emergency in 1975.
"We had scores of sources throughout the Indian government," the book quotes former KGB general Oleg Kalugin as saying.
"It seemed like the entire country was for sale."
Congress Party general secretary Ambika Soni told the BBC the author had no evidence for his claims.
She said his book showed he had not one iota of knowledge about India.