Sri Lanka lost the match at Mumbai's Wankhede stadium by six wickets. Indian players have strongly denied any wrongdoing.
Ranatunga, who was at the stadium as a commentator, has previously called for an investigation into the defeat.
"When we lost, I was distressed and I had a doubt," he said in July 2017. "We must investigate what happened to Sri Lanka at the 2011 World Cup final."
"I cannot reveal everything now, but one day I will. There must be an inquiry," added Ranatunga, who said players could not hide the "dirt".
Sri Lanka batted first and scored 274-6 off 50 overs. They appeared in a commanding position when Indian superstar Sachin Tendulkar was out for 18.
But India turned the game dramatically, thanks partly to poor fielding and bowling by Sri Lanka, who were led by Kumar Sangakkara.
Sri Lankan cricket has regularly been involved in corruption controversies, including claims of match-fixing ahead of a 2018 Test against England.
Earlier this month, the Sri Lankan cricket board said the International Cricket Council was investigating three unnamed former players over alleged corruption.
Sri Lanka introduced tough penalties for match-fixing and tightened sports betting restrictions in November in a bid to stamp out graft.
Another former sports minister, Harin Fernando, has said Sri Lankan cricket was riddled with graft "from top to bottom", and that the ICC considered Sri Lanka one of the world's most corrupt nations.
Former Sri Lankan fast bowler Dilhara Lokuhettige was suspended in 2018 for corruption relating to a limited-overs league.
He was the third Sri Lankan charged under the ICC anti-corruption code, following former captain and ex-chief selector Sanath Jayasuriya, and former paceman Nuwan Zoysa.
Jayasuriya was found guilty of failing to co-operate with a match-fixing probe and banned for two years. Zoysa was suspended for match-fixing.