Sudanese security forces fired tear gas at protesters who were taking part in pro-democracy demonstrations in the capital, Khartoum on Monday.
Teachers taking part in one protest were detained by the security forces.
Overnight demonstrators set up barricades for the first of two days of planned civil disobedience to protest against last month’s coup.
They are demanding the military government step back and allow a peaceful transition to civilian rule.
The 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 facing pressure from the military to co-operate with them.
Last month, Gen Abdel Fattah al-Burhan, the coup leader, disbanded the civilian arm of the government’s power-sharing arrangement, jailed civilian leaders, and declared a state of emergency.
