UN High Commissioner for Human Rights Michelle Bachelet holds a news conference at Centro Cultural Espana in downtown Mexico City, Mexico April 9, 2019 REUTERS/Carlos Jasso

GENEVA (Reuters) - Sudanese authorities should release people held for peacefully protesting and investigate the use of force against demonstrations since December, U.N. human rights chief Michelle Bachelet said in a statement on Friday.

“This is a very critical, volatile moment for Sudan and there is deep uncertainty and unease about the future,” Bachelet said, adding that the authorities must refrain from using force against peaceful protestors.

Thousands are camped outside the defence ministry in Khartoum to push for a civilian government, defying a curfew and calling for mass prayers after the military overthrew Omar al-Bashir after 30 years of autocratic rule.