During the appeal hearing in March, the prosecutor had asked the judges to sentence the officer to life in prison.
"The 25-year sentence does not reflect the intrinsic gravity of the crime of incitement to commit genocide especially that it was perpetrated by an officer of the rank of Colonel", argued the prosecution.
The First Instance Chamber had concluded that Muvunyi had gone to at least two places in the prefecture of Butare, southern Rwanda, in 1994 and had called on Hutu civilians to kill ethnic Tutsis.
"His position of the highest ranking officer in the prefecture inciting Hutu peasants to commit genocide should have been regarded as an aggravating circumstance", claimed the prosecution, adding that the crime of incitement to commit genocide is one of the gravest crimes which, by itself, deserved life imprisonment.
During his closing remarks, Muvunyi, who faces crimes committed in 1994 by soldiers of the School of Warrant Officers (ESO) of Butare, has strongly denied ever having been commander of the military academy.
He had also affirmed that he did not have any authority to punish the guilty soldiers. "There was no official text or any communication which named me to this position", he stated, pleading with the appeal judges to acquit him.
Immediately after the ruling, , the judges will hold a one-day plenary on Friday, according to acting Registrar of ICTR, Everard O'Donnell.
The plenary is held in closed session and mainly dwells with technical matters with the viewing to enhancing efficiency of the tribunal. It is also expected to review the ICTR's exit strategy.
The last plenary was held in March, this year.
The Appeals Chamber Thursday heard an appeal of former Governor of Kigali Rural, Francois Karera, who is seeking dismissal of his life sentence imposed by the lower court in December, 2007 for his role in the 1994 genocide. The date for judgement will be announced later.
© Hirondelle News Agency