A U.S.-based advocacy group says 98 girls in Central African Republic reported they were sexually abused by international peacekeepers, and three girls told U.N. staff they were tied up, undressed and forced to have sex with a dog by a French military commander in 2014.

AIDS-Free World's Code Blue Campaign to end sexual abuse and exploitation said the three girls told a U.N. human rights officer that a fourth girl tied up with them later died of an unknown disease.

The group said the information it received, including the alleged rape of a 16-year-old girl in another part of the country on Monday, is in the hands of senior U.N. officials.

The reports of new allegations of sexual exploitation and abuse committed by UN and non-UN personnel in the Central African Republic are sickening," U.S. Ambassador Samantha
Power said.

Earlier this month the U.N. Security Council adopted a U.S.-drafted resolution endorsing Secretary General Ban Ki-moon’s recommendation to repatriate peacekeeping units believed to have engaged in sexual exploitation and abuse.

“Sadly history has shown us that unless you keep the pressure on these issues, unless you expose the abusers, then the abuse continues,” Philippe Bolopion with Human Rights Watch tells Fox News. “Countries that contribute peacekeepers have far too long let abusive troops off the hook,” Bolopion added.

The U.N. human rights chief, Zeid Ra'ad Al Hussein, in a statement Thursday called the allegations "sickening" and said all three countries whose peacekeepers are accused have been formally notified. He said countries must do more to stop abuse and hold their troops accountable, "otherwise this awful cycle of abuse will never end."

There was no immediate comment from French authorities.

The United Nations has been in the spotlight for months over allegations of child rape and other sexual abuses by its peacekeepers, especially those based in Central African Republic. There have been similar allegations against the French force known as Sangaris, which operates independently in Central African Republic, known as CAR.

U.N. spokesman Stephane Dujarric said last week that a U.N. team was sent to gather information about recently reported allegations of sexual abuse and exploitation by U.N. and non-U.N. forces as well as civilians in Kemo prefecture, east of the capital Bangui, in 2014 and 2015.

Dujarric said in a note to correspondents Wednesday evening that the new allegations went back to 2013 and included allegations against local armed groups. He said a U.N. team is on the ground and the exact number and nature of "these extremely troubling allegations" is still being determined.

The team has identified the alleged involvement of U.N. contingents from Burundi and Gabon, which will remain confined to camps during the investigation, Dujarric said. Allegations against French forces in the same area are also being investigated, he said.

The U.N. recently reported that 25 allegations of sexual abuse and exploitation were registered with the U.N. mission in Central African Republic in January and February, most from previous years. This compares with a total of six allegations in the 15 other U.N. peacekeeping missions in the first two months of this year, the U.N. peacekeeping department said.

A U.N. report earlier this month said there were 69 allegations of sexual abuse and exploitation by peacekeepers in 2015 -- 22 of them in CAR.

Central African Republic has been rocked by sectarian violence since 2013.

AIDS-Free World called the information it received "shocking." Two weeks ago, it said, the U.N. children's agency UNICEF interviewed 98 girls who reported being sexually abused.

The group said that Saturday a delegation from the U.N. peacekeeping mission known as MINUSCA met local leaders and victims who alleged that troops from France and Gabon had sexually abused girls. Some victims left the area because they were stigmatized by the community, it said.

During the delegation's visit, AIDS-Free World said the three girls reported being tied up inside a camp by the French military commander. After having sex with the dog, the group said, each girl was given 5,000 Central African Francs, or about $9.

One girl told the U.N. human rights officer that the fourth girl who later died "was called `the Sangaris' dog' by people in the community."

AIDS-Free World also said the mother of a 16-year-old girl informed local police in another part of CAR that a Congolese U.N. peacekeeper raped her daughter in a hotel room Monday afternoon.

The group said that when the soldier was questioned by police in the presence of his commander he confirmed that he "had sexual intercourse" with the victim several times and paid her between 2,000 and 5,000 Central African Francs.

Fox News' Jonathan Wachtel and The Associated Press contributed to this report.