NAIROBI, Kenya - The U.N. peacekeeping mission in Congo is collaborating with known human-rights abusers as it backs a brutal Congolese military operation that has led to the deliberate killing of at least 1,400 civilians and a huge surge in rapes, Human Rights Watch said in a report.

The group's 183-page report, the fullest accounting so far of the operation, is a chronicle of horrors. It describes civilians being tied together before their throats are slit, gang rapes, massacres, and village burnings - much of it carried out by a Congolese army being fed, transported, and otherwise supported by the United Nations.

The report calls for the U.N. peacekeeping mission to "immediately cease all support" to the Congolese army until the army removes commanders with known records of human-rights abuses and otherwise ensures the operation complies with international humanitarian laws.

"Continued killing and rape by all sides in eastern Congo shows that the U.N. Security Council needs a new approach to protect civilians," said Anneke Van Woudenberg, senior research with Human Rights Watch.

The Security Council is scheduled to meet this week to discuss the Congolese peacekeeping mission's mandate - the United Nations' largest and most expensive. A mission spokesman said officials were studying the report and declined to comment. The United States also has a small military team in Congo assisting the Congolese army.

U.N. Secretary-General Ban Ki-moon said yesterday that he was "not sure whether it is desirable to suspend all peacekeeping operations."

The Congolese military operations began in January and were intended to root out abusive Rwandan rebels who have lived mostly by force among eastern Congolese villagers for years, fueling a long-running conflict that is the deadliest since World War II.

The rebels - the Democratic Forces for the Liberation of Rwanda, or FDLR - include some leaders accused of participating in the 1994 genocide in neighboring Rwanda.

Rwandan troops backed the initial phase of the military operations. But as they departed in February, U.N. peacekeepers stepped in, supplying attack helicopters, trucks, food, and other logistical support to a Congolese army known as one of the world's most abusive militaries. At the time, Alan Doss, head of the U.N. mission, said that the operations were necessary and that some civilian casualties were inevitable.

Human Rights Watch did not document the story of civilians accidentally caught in the cross fire. Instead, its report details a chilling pattern of deliberate civilian killings by Congolese and Rwandan soldiers and the rebels they are fighting. Both sides, the report says, have carried out a strategy of "punishing" villagers they accuse of supporting the wrong side.

To that end, the report says, Congolese soldiers and their Rwandan allies did not simply shoot their victims but beat them to death with clubs, stabbed them to death with bayonets, or chopped them into pieces with machetes, making a pile of body parts for other villagers to see.

The report documents a similarly ruthless pattern of retaliation by the FDLR, who killed with machetes and hoes, accusing villagers of betraying them. It says the rebels often targeted village chiefs or other influential people to frighten others.

The United Nations last month halted support to a Congolese brigade that allegedly killed at least 62 civilians in one province. Ban said further suspensions would be ordered when the United Nations has grounds to believe that Congolese or Rwandan forces might violate human-rights laws.