Forces loyal to Ivory Coast's democratically elected president killed hundreds of civilians, raped his rival's supporters and burned villages during an offensive launched in the country's west, a human rights group said.
Human Rights Watch called on Alassane Ouattara to investigate and prosecute abuses by his forces and those supporting his rival, strongman Laurent Gbagbo.
The group also said that forces loyal to Gbagbo killed more than 100 civilians to retaliate against pro-Ouattara fighters who launched a major offensive advancing toward Abidjan.
Gbagbo is holed up in a bunker in his residence in Abidjan. After a decade in power, he still refuses to step aside even though the United Nations has ruled that he lost the November presidential election to Ouattara.
After four months of diplomacy, Ouattara gave the go-ahead for a military intervention led by fighters from a former rebel group. They swept across the country, advancing hundreds of miles (kilometers) and taking dozens of cities in a matter of days before being held up at the door of Abidjan, Ivory Coast's biggest and most strategically important city.
The United Nations on Sunday said that the Golf Hotel in Abidjan where Ouattara is based came under attack late Saturday and one peacekeeper was injured.
U.N. spokesman Hamadoun Toure said that rockets and mortars landed on the hotel grounds shortly after U.N. forces came under attack nearby on Saturday evening. One peacekeeper was evacuated to hospital with serious injuries, he said.
Massere Toure, a communications adviser for Ouattara, denied that the hotel itself was targeted by the attack, which she said started when a patrol sent out from the hotel was ambushed by forces loyal to former president Gbagbo.
Toure confirmed that stray bullets and at least one mortar landed on hotel grounds during the fighting.
Gbagbo's forces broke out of the presidential compound Saturday and advanced into position in the downtown core and near the Golf Hotel.
But the human rights group warned there is more going on outside Abidjan.
"While the international community has been focused on the political stalemate in Abidjan over the presidency, forces on both sides have committed numerous atrocities against civilians, their leaders showing little interest in reining them in," said Daniel Bekele, Human Rights Watch Africa director in the report obtained by The Associated Press late Saurday.
People interviewed by the group described how pro-Ouattara forces "summarily executed and raped perceived Gbagbo supporters in their homes, as they worked in the fields, as they fled, or as they tried to hide in the bush."
The report said that many of the abuses occurred from March 6-30, as vllages in the west including Toulepleu, Doke, Blolequin, Duekoue and Guiglo fell to pro-Ouattara forces.
The U.N. said peacekeepers and human rights officials discovered about 60 bodies in the western town of Guiglo. The U.N. human rights agency said another 40 corpses were found lying the street in Bloleqin, and many of them had been shot. Fifteen other bodies were found in Duekoue, where violence already has left at least 229 dead in recent weeks.
The report said that many were targeted for their ethnicity and Ouattara's Republican forces have killed, raped, and pillaged the predominantly Guere population who largely supported Gbagbo in the election. Abuses continued through March, culminating in the massacre of hundreds in Douekoue on March 29, the report said.
On Sunday, rebels at roadblocks in Carrefour were armed with Kalashnikov rifles, AK-47's, shotguns, hunting rifles and knives. They stood across fom homes charred shells of homes.
Thousands of people gathered at the Roman Catholic Mission of St. Theresa of the Baby Jesus, which has become a refuge for 30,000 people. Rice was being distributed and Medecins Sans Frontieres had set up a clinic.
Ouattara had long tried to distance himself from the orthern-based fighters taking up his cause who fought in a brief civil war almost a decade ago that left the country split in two. Those fighters were accused of many atrocities at the time. But he appeared to change tack as the rebel fighters, which he renamed the "Republican Forces," began their lightnig assault on Abidjan.
In recent weeks, a pro-Gbagbo militia had also been targeting Ouattara supporters, refugees told the AP.
On March 28, pro-Gbagbo forces massacred more than 100 people in Blolequin, and killed 10 more northerners and West African immigrants in the town of Guiglo, the group said.
"To understand the tragic events in Ivory Coast, a line cannot be drawn between north and south, or supporters of Gbagbo and Ouattara," Bekele said. "Unfortunately, there are those on both sides who have shown little regard for the dignity of human life."
In the report, Human Rights Watch called on Outtara to "take decisive measures to address serious violations of international law by all forces, prevent further reprisals and acts of collective punishment, and urgently investigate and prosecute all those responsible for abuses."
More than a million people have fled their homes since the November elections, with some 130,000 cross the border to Liberia.
In Paris on Sunday, Gbagbo adviser Toussaint Alain said the state administrator for Abidjan, Sam Etiasse, and one of his predecessors, Col. Kone Al Mustapha, were kidnapped from their homes on Saturday by "armed groups" loyal to Ouattara and taken to an unidentified location. But the accusations could not be immediately verified.
Associated Press writer Marco Chown Oved in Abidjan, Ivory Coast and Jamey Keaten in Paris contributed to this report.