Elements of the Congolese army and national police "were responsible for a large number of serious human rights violations during the reporting period, namely arbitrary executions, rape, torture and cruel, inhuman and degrading treatment", he said.
Rebels, including Gen Nkunda's Tutsi CNDP and the Rwandan Hutu FDLR militia - some of whose fighters are believed to have taken part in the 1994 Rwandan genocide - were meanwhile accused of perpetrating "serious human rights abuses with impunity".
These included "mass killings, torture, abductions, forced recruitment of children, forced displacement and destruction of [refugee] camps, force labour, sexual violence", the report added.
The Congolese national civilian and military intelligence services were also accused of making arbitrary arrests, followed by "torture and extortion".
Last week, the Security Council approved an additional 3,000 soldiers and police for the UN peacekeeping mission in DR Congo in an effort to prevent the conflict in the east escalating.
The recent violence has triggered a humanitarian crisis, forcing an estimated 250,000 people to flee their homes. Aid agencies have struggled to assist those most affected by the violence.
On Monday, a UK-based aid group said it had been able to get medical supplies to the towns of Kanyabayonga and Kirumba for the first time since they were captured by rebels 10 days ago.
Aid is distributed in DR Congo
Mr Ban's special envoy, Olusegun Obasanjo, has urged Congolese President Joseph Kabila to talk with Gen Nkunda in order to prevent the situation from worsening.
Gen Nkunda had three demands, Mr Obasanjo said: direct talks with the government, protection of minorities and integration of his soldiers into military and administrative structures.
Human Rights Watch, meanwhile, accused Mr Kabila's government of "brutal repression" following polls in July 2006 aimed at bringing democracy to the country after years of fighting.
Five hundred political opponents had been killed since then in the capital, Kinshasa, and the western province of Bas Congo, it said in its report, and another 1,000 had been detained.
Many of those held reported being tortured, the rights group said.
Efforts to build a democratic nation were being stifled not just by the fighting in the east of the country but "by the Kabila government's repression", Anneke Van Woudenberg, a senior researcher for HRW, said in a statement.
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