Khartoum — SUDANESE security forces have killed at least 40 people after firing live ammunition on protesters demanding the resignation of President Omar al-Bashir.
Human rights groups and medical workers said among those killed are children.
Scores of protesters have been injured and others arbitrarily detained during demonstrations triggered by increases in the price of food and fuel.
The protests began late December in the northeastern Atbara and have spread to other cities and towns countrywide.
Authorities have deployed national security forces, police and the paramilitary Rapid Support Forces to quell the demonstrations.
In many places, they used excessive force to disperse unarmed protesters, beating them with batons and firing live ammunition, rubber bullets and teargas.
Human Rights Watch (HRW) called on government to investigate all violations and hold responsible personnel to account.
"Sudanese have the right to protest peacefully and express their views without risking life or limb or getting locked up," said Jehanne Henry, associate Africa director at HRW.
Government officials acknowledged that 19 people were killed and over 800 arrested but blame protesters and so-called saboteurs for the violence.
Al-Bashir announced his government was investigating events that led to the loss of lives.
More than 170 protesters were killed, most by bullet wounds, during Sudan's clampdown on protests in 2013. Investigations did not result in credible prosecutions.
Al-Bashir is wanted by the International Criminal Court for alleged genocide, crimes against humanity and war crimes in Darfur.