The probe by the Board of Control for Cricket in India (BCCI)'s anti-corruption chief Ravi Sawani, also found two other players guilty of not reporting approaches made by bookmakers, The Indian Express said.
Sreesanth, Ajit Chandila and Ankeet Chavan were found guilty on multiple accounts, including conceding a "pre-determined number of runs per over in exchange for bribes", the paper quoted the leaked report as saying.
The fourth player, Amit Singh, who played in the IPL till last year, was seen as the conduit between the cricketers and bookies, and described by Sawani as "the bad fish that spoils the entire pond".
Siddharth Trivedi and 21-year-old Harmeet Singh were absolved of spot-fixing, but were found guilty of the lesser charge of not informing officials about approaches made by bookmakers, the newspaper said.
Sawani, whose report will be placed before the BCCI's disciplinary committee, has recommended the players be banned for a period ranging from five years to life, the paper said.
"The disciplinary committee may consider my report and impose such sanctions as considered appropriate to send out a strong signal indicating the zero tolerance policy of the BCCI to any corruption in the sport that is so dear to millions of Indians and fans abroad," the paper quoted Sawani as saying in the report.
"Obviously, the anti-corruption education given to the players had no impact on the conduct. Therefore, the players deserve no leniency whatsoever."
A BCCI spokesman declined to comment on the leaked newspaper story, saying Sawani's findings would be discussed by the disciplinary committee and may be placed before the board's annual general meeting on September 29.
The four players found guilty of spot-fixing are among 39 persons who have also been charged separately by Delhi Police in the corruption scandal that rocked this year's IPL.
All four players belong to the Rajasthan Royals franchise, but Sreesanth, 30, is the only one to have played for India. He was part of the teams that won the World Twenty20 in 2007 and the World Cup in 2011.
The players were arrested in May along with scores of bookies as part of a police investigation into the spot-fixing scandal, which had caused outrage among fans in the cricket-mad nation.
BCCI chief Narayanaswami Srinivasan voluntarily stepped aside from the post in June after his son-in-law was arrested, and later released on bail, over alleged links to illegal bookmakers.
Son-in-law Gurunath Meiyappan is one of the owners of IPL franchise Chennai Super Kings, a team bought by Srinivasan's India Cements conglomerate when the popular Twenty20 league was launched in 2008.
Gambling is mostly illegal in India, but betting on cricket matches thrives through networks of underground bookies.
Spot-fixing -- in which a specific part of a game, but not the result, is fixed -- is also illegal.