Sudanese security forces fired tear gas at demonstrators who were participating in pro-democracy demonstrations in the capital, Khartoum.
Teachers who took part in a protest were arrested by the security forces.
Overnight protesters erected barricades for the first of two days of planned civil disobedience to protest last month’s coup.
They ask the military government to step back and allow for a peaceful transition to civilian government.
Demonstrations are happening as Arab League mediators arrive in Khartoum for talks to try to defuse the crisis.
The civilian prime minister, Abdalla Hamdok, remains under house arrest and is being pressured by the military to cooperate with them, reports BBC’s Andrew Harding from the capital.
Last month, coup leader General Abdel Fattah al-Burhan dissolved the civilian arm of the government’s power-sharing agreement, arrested civilian leaders and declared a state of emergency.
The internet outages had left some people in the dark about the two-day civil disobedience action, but teachers showed up to protest near the education ministry.
“We have organized a silent stance against Burhan’s decisions outside the education ministry,” Mohamed al-Amin, a geography teacher, told AFP news agency.
“Later the police came and shot us tear gas even though we were just standing in the streets carrying banners.”
In north Khartoum, security forces patrolled main roads carrying canes and tear gas grenades, Reuters added.
“The military will not dominate us”
Victims of military repression are treated in the Royal Care private hospital in Khartoum.
Muhayed Faisal, an 18-year-old student, was shot twice in the leg during a recent protest. “They shot me along with nine people. There were no warning shots, they just started shooting. The military … they are like animals. Maybe animals are better.”
Now he has undergone three operations on his right leg: “Our cause has not changed: the military will not dominate us,” he said, while a doctor stroked his foot to check if any sensation had returned.
In a nearby bed, a 54-year-old tailor, Yair Mohamed Ali Abdulla, was surrounded by relatives. He had left his shop to join the protests when the coup took place. He said he was deliberately run over by soldiers in a vehicle near Khartoum International Airport.
“After that, five or six people mercilessly beat me with sticks on the back and chest. I just went [to the protest] to ask for freedom, peace and justice. If the military can’t provide it, they should take off their uniforms and let whoever can come and take command, “he said.