Aisha Musa, one of only two women on Sudan's ruling Sovereign Council, said on Saturday that she was holding onto her resignation.
"The civilian component in the Sovereign (Council) and at all levels of government has become just a logistical executive body that does not participate in decision-making," Musa said in a video statement carried by the state news agency SUNA.
"Rather it only stamps the approval of pre-prepared decisions," she added.
The 14-member military-civilian council was set up along with a cabinet of technocrats to steer Sudan through a transition after the army toppled Omar al-Bashir in 2019.
Musa said she had submitted her resignation on May 12, a day after the killing of two protesters who had been marking the anniversary of a deadly raid on a protest site during the 2019 uprising. She accused the transitional authorities of leading the country to "more killing, injustice, poverty and suffering."
Musa complained that the investigation into the 2019 raid had not yet been completed and its results had not been revealed. Activists say 130 people died in that raid and ensuing violence; the authorities have acknowledged 87 deaths.
Medics, protest groups and eyewitnesses have said security forces fired live rounds and tear gas at demonstrators marking the anniversary this month.