At least 128 people were killed when Guinean troops opened fire on opposition protesters on Monday, rights groups and opposition figures claim, BBC reported.
Earlier police said 87 people had died, but local activists say hospital sources confirmed a much higher toll.
Human rights groups say they have had reports of soldiers bayoneting people and women being stripped and raped in the streets during the protest.
Junta head Capt Moussa Dadis Camara denied knowledge of sexual assaults.
But he admitted that some of his security forces had lost control.
French Foreign Minister Bernard Kouchner said France was suspending military ties with Guinea after the "savage and bloody" crackdown on opposition protesters, the French news agency AFP reported.