The United Nations said it will repatriate nine peacekeepers from a South African contingent in eastern Congo who were accused of sexual assault and other abuse.

The U.N. decided to immediately repatriate the peacekeepers and a senior officer of the South African army “due to the seriousness of the allegations against them,” the organization said in a statement on Friday.

The senior officer allegedly tried to hinder a probe into the allegations and threatened other peacekeepers. Two other indicted senior officers will also be replaced, the U.N. said.

More than 12,000 U.N. peacekeepers are deployed in eastern Congo, where more than 100 armed groups are active.

The U.N. said its preliminary assessment found that the nine peacekeepers were “fraternizing after curfew hours” in prohibited bars where prostitution takes place. The soldiers were also alleged to have assaulted staff of the peacekeeping mission and the military police who were trying to arrest them, the statement added.

South African authorities have indicated their “full cooperation, in particular through the deployment of a national investigator,” the U.N. said, promising that victims would be assisted and that the peacekeeping mission would remain committed to upholding U.N. standards.

Such accusations of sexual abuse by U.N. peacekeepers are not new in various parts of the world, from Congo to Haiti where peacekeepers are deployed. The victims in many instances are children.

The abuses are particularly rampant in Congo, which accounted for one-third of the nearly 2,000 sexual abuse and exploitation complaints made against the U.N. worldwide in 2017.

The U.N. has also been accused of not doing enough in handling such allegations. Last year, Secretary-General António Guterres said the organization has “not succeeded in all respects, but neither have we stood still” in handling the sexual abuse crisis.