Ahead of the FIFA presidential election on Friday, Platini said the 79-year-old Blatter had no grand plans for FIFA and it was ''not credible'' to claim he needed a fifth four-year term to complete an unfinished mission.
''No, he is simply scared of the future, as he has given his life to the institution, to the point where he now identifies himself fully with FIFA,'' Platini said. ''I understand the fear of that emptiness that he (Blatter) must have, it's natural. But if he really loves FIFA, he should have put its interests ahead of his own.''
Though Platini said he likes Blatter on a personal level, his explicit criticism of the FIFA chief points to a deep rift between the two men. Blatter seeks to extend his 17-year reign at an election many saw as a natural time for the former France great to get the top job.
He opted last August not to challenge Blatter in the election of 209 FIFA member federations and now supports the only opponent: FIFA vice president Prince Ali bin al-Hussein of Jordan.
''I am firmly convinced that Ali, whom I have known on a personal level for years, would make a great FIFA President. He has everything it takes,'' Platini said of the prince, praising his ''great freedom of spirit and independence.''
However, Blatter is strongly favored to win another vote with widespread support in five of FIFA's six continental regions. He noted his longevity in office in a newspaper interview in his native Switzerland on Sunday.
Blatter compared himself to a mountain goat, telling the Neue Zurcher Zeitung he ''cannot be stopped, I just keep going.''
Platini, now 59, was a key campaigner helping Blatter become FIFA president in 1998 and then a long-time heir apparent.
''I have nothing against Sepp. I like him as a person and I respect him,'' Platini said in an interview transcript provided by UEFA. ''We have had some good times together, and nothing and no one can take that away.''
Still, Platini has not forgiven Blatter for going back on a promise at the 2011 UEFA Congress in Paris that the current FIFA mandate would be his last. Blatter has since said he had the right to change his mind.
''And now here we are again, as if none of it had ever happened,'' said the UEFA president, adding he felt he asked his members four years ago to support Blatter ''on the basis of a lie.''
Then, Blatter was in a battle with Mohamed bin Hammam of Qatar who withdrew days before the election when accused of offering Caribbean voters $40,000 bribes.
FIFA and Blatter have spent much of the past four years handling fallout and reputational damage from scandals involving Bin Hammam and other senior executive committee members, plus the controversial choices of Russia and Qatar as World Cup hosts in 2018 and 2022, respectively.
''And while he remains in place, whether he likes it or not, and whether it is fair or not, FIFA will lack credibility and its image will be tarnished, and so it will lack authority.
''Moreover, it will be football that suffers,'' Platini said, though acknowledging that Blatter had ''done some very good things.''
''FIFA will not disappear the moment he steps down. On the contrary, it would give FIFA the chance of a new lease of life,'' he said.
Prince Ali offers that chance, ''is always very positive and fights for what he believes in,'' Platini said. ''(H)e is honest and humble and comes from a country that bridges different cultures and traditions. He can bring real added value, and he is also someone who knows how to work in a team.''