Both sides in Sudan's civil war have committed abuses that may amount to war crimes including indiscriminate attacks on civilian sites like hospitals, markets and even camps for the displaced, the United Nations (UN) human rights office said on Friday.

Efforts have so far failed to end the 10-month-old conflict that pits Sudan's regular armed forces and the paramilitary Rapid Support Forces (RSF). Thousands of people have been killed and over six million forced to flee their homes, making it the country with the largest displaced population in the world.

"Some of these violations would amount to war crimes," Volker Turk, the UN High Commissioner for Human Rights, said in a statement accompanying the report. "The guns must be silenced, and civilians must be protected."

The US has already formally determined that the warring parties have committed war crimes and said the RSF and allied militias were involved in ethnic cleansing in West Darfur. Both sides have said they would investigate reports of killings and abuses and prosecute any fighters found to be involved.

The United Nations report covers the April-December period and is based on interviews with over 300 victims and witnesses as well as footage and satellite imagery.

It says that sometimes those fleeing for their lives or displaced by the violence became victims of explosive weapons attacks.

In one incident, dozens of displaced people were killed when their camp in Zalingei, Darfur was shelled by RSF between September 14 and 17, the report said. Some 26 civilians, mostly women and children, were killed on August 22 by shells reportedly fired by the Sudanese Armed Forces while sheltering under a bridge.

The report also says the RSF had adopted a military strategy of using human shields, citing testimonies of victims involved.

It describes incidents in the capital Khartoum where dozens of individuals were arrested and placed outside near RSF military posts to deter air strikes from Sudanese fighter jets.

UN investigators have so far documented cases of sexual violence affecting 118 people, including one women who was detained and repeatedly gang-raped for weeks. Many of the rapes were committed by RSF members, it said.

Reuters has also documented cases of gang rape in ethnically targeted attacks by RSF forces and allied Arab militia.

The war erupted last April over disputes about the powers of the army and the RSF under an internationally-backed plan for a political transition towards civilian rule and free elections.