Sudanese security agents raided the headquarters of a human rights monitor Sunday and seized computers, a member of the group said, nearly two weeks after one of its founders was arrested.

National Intelligence and Security Service (NISS) agents arrived at the office of the Sudan Human Rights Monitor in the early afternoon and searched the premises.

South Sudan rebels killed, raped and kidnapped civilians during an attack in October, leaving at least 11 dead, the United Nations said in a report.

Fighters backing former vice president Riek Machar attacked the oil-rich town of Bentiu near the border with Sudan on October 29 and "killed at least 11 civilians and committed other serious human rights abuses," said the report, received by Agence France Presse on Saturday.

Human Rights Watch on Monday accused Sudanese government forces and allied militias of leading a campaign of killings and rapes in areas of Blue Nile state where they are battling insurgents.

Khartoum has been struggling to crush an insurgency in Blue Nile and neighboring South Kordofan since 2011, when the Sudan Peoples Liberation Movement-North (SPLM-N) mounted a revolt.

War in South Sudan is worsening with "extreme violence" and growing hunger, rights groups warned Monday, one year since the start of conflict in which tens of thousands have died.

Campaigners say South Sudan is locked in conflict, with the bloodshed that erupted in Juba exactly a year ago having set off a cycle of retaliatory massacres across large swathes of the country.

Nobel peace prize winners on Sunday expressed deep concern about the growing threat of conflict, including nuclear war, and "a new and more dangerous Cold War."

Sudanese President Omar al-Bashir on Saturday hailed the International Criminal Court's suspension of its investigations into alleged war crimes in Darfur, accusing it of trying to "humiliate and subjugate" his country.

Bashir is wanted by the ICC over alleged war crimes in the western region, where the government has been trying to crush an insurgency since 2003.

International Criminal Court prosecutor Fatou Bensouda said Friday she has suspended investigations into alleged war crimes in Sudan's Darfur, criticizing the U.N. Security Council for inaction over the conflict-hit region.

"I am left with no choice but to hibernate investigative activities in Darfur as I shift resources to other urgent cases," Bensouda told the Security Council.

A year of civil war in South Sudan has devastated the world's youngest nation.

Here are figures showing the impact of the fighting since war broke out on December 15, 2013, based on UN, aid agency and diplomatic assessments.

International Criminal Court prosecutor Fatou Bensouda rebuked the U.N. Security Council on Friday for failing to push for the arrest of Sudanese President Omar Bashir for crimes committed in Darfur.

The U.N. human rights office expressed deep concern on Friday about the arrests of opposition figures and rights activists in Sudan.

"We're deeply concerned about a pattern of detentions and prosecutions in Sudan in recent months that appear aimed at silencing political opposition and criticism of the policies of the ruling party," spokeswoman Ravina Shamdasani told reporters in Geneva.