The call to protest on August 17 came after the National Front for the Defense of the Constitution (FNDC) -- an influential alliance of political parties, trade unions and civil society organizations -- halted demonstrations following deadly clashes and a plea for calm by West Africa's regional bloc.
In a statement released Monday, the FNDC denounced the junta's "contemptuous and arrogant refusal to respond to the numerous calls for dialogue on the transition" and its "chronically defiant attitude towards the regional and international community".
It also denounced the military leaders' "illegal use of lethal weapons in managing demonstrations".
It demanded that the junta open a framework for "credible dialogue" with political and civil society groups, set a "reasonable and consensual" deadline for the return to democracy and unconditionally release all political detainees linked to the demonstrations.
Two of the coalition's leaders -- Oumar Sylla, alias Fonike Mangue, and Ibrahima Diallo -- as well as Saikou Yaya Barry, the executive secretary of the Union of Republican Forces (UFR) political party, were still being held Monday in Conakry's civil prison.
They have been charged with unlawful assembly, looting, the destruction of property and intentional assault and battery.
On Monday, Sylla's lawyer told local media that the FNDC leader did not "recognize" what he is accused of and believes he is "within his rights to fight for the establishment of democracy."
Colonel Mamady Doumbouya, who overthrew ex-president Alpha Conde last September, pledged to return power to elected civilians within three years, a transition period that regional powers and most domestic political actors have rejected, with ECOWAS suspending Guinea after the coup.