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The U.S. ambassador to the U.N. is disputing accounts that the U.S. Embassy remained idle while South Sudanese forces last month allegedly raped, beat and robbed people in a residential complex home to foreign aid workers, including Americans.

U.S. Ambassador Samantha Power said the U.S. Embassy in Juba, the beleaguered capital of South Sudan, did in fact respond to distress calls from the compound and "urgently contacted South Sudanese government officials, who sent a response force to the site to stop the attack."

Related: South Sudan Troops Raped, Beat Foreigners as U.N. Force Ignored Calls for Help: AP

Witnesses have accused other embassies and the U.N.'s peacekeeping force of failing to come to their aid amid the July 11 attack on the Terrain Hotel Complex.

Some of the more than 30,000 Nuer civilians sheltering in a United Nations base in South Sudan's capital Juba on July 25, 2016. Jason Patinkin / AP

"We are deeply concerned that United Nations peacekeepers were apparently either incapable of or unwilling to respond to calls for help," Power said in a statement Monday.

She added that the U.S. is demanding the U.N. to take "swift corrective action" if the allegations against its peacekeepers is found to be true. The U.N. is investigating the claims.

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The four-hour assault was brought to light in an Associated Press report Monday, in which several witnesses recounted the rampage by South Sudanese soldiers and lack of response.

The group Human Rights Watch also said in a report about the incident that "the peacekeepers did not venture out of the bases to protect civilians under imminent threat."

The U.N. and U.S. embassies are accused of ignoring desperate pleas for help, witnesses said.

"All of us were contacting whoever we could contact," one woman, who said she was raped by 15 men, told the AP. "The U.N., the U.S. embassy, contacting the specific battalions in the U.N., contacting specific departments."

Related: 'Several Hundred' Dead After Clashes

South Sudan, the world's youngest country, has been mired in violence and poverty since its independence from Sudan in 2011.

Forces loyal to South Sudan President Salva Kiir have been locked in a civil war with supporters of Vice President Riek Machar, a former rebel leader. Despite a peace deal last year, fighting persists, and people have been targeted based on their ethnic identities.

South Sudanese soldiers are seen along a street following renewed fighting in Juba on July 10, 2016. REUTERS

The Terrain Hotel became a target after government forces won a battle in the city and celebrating soldiers rolled in. Those who took part in the horrific acts had shoulder patches with the face of a tiger — the insignia worn by the president's personal guard, witnesses told the AP.

In some cases, the soldiers asked people if they were American, and if they said yes, they were hit with belts or the butt of their guns, the witnesses said. A South Sudanese journalist was killed while foreigners were forced to watch, they added.

The U.S. State Department said that once it learned about what was happening, it contacted South Sudan's National Security Service and the Presidential Guard to secure the scene. Some 80 Americans were moved to safety amid the chaos.

U.S. officials have "raised the incident" with senior officials in the U.N. Department of Peacekeeping Operation, said State Department spokeswoman Elizabeth Trudeau.

"We condemn these attacks," she told reporters Monday. "We have called for accountability for those who are involved in the violence."

President Kiir said this week he would consider a plan by the U.N. to send troops to South Sudan after the U.N. Security Council last week authorized deploying 4,000 officers there in light of the violence.