The entire unit of 120 officers was sent home from its peacekeeping mission earlier this month.

Nigeria's police chief said the punishment would serve as an example to other police officers.

The UN mission in DR Congo has been hit by repeated accusations of sexual abuse against local girls and women.

As a result, a new code of conduct was introduced for the peacekeepers, which banned any sexual relations with Congolese women.

"Investigations so far conducted have established corroborated cases against 11 officers, including your commander who breached the UN Code of Conduct," said Nigerian police chief Sunday Ehindero.

"You all have brought shame to this country," he said in a speech to the entire unit.

Explaining the decision to pull out the whole group two weeks ago, Nigerian police spokesman Haz Iwendi said: "When one is contaminated, the whole bunch is contaminated."

The UN mission in DR Congo is the world's largest peacekeeping operation with some 19,000 staff trying to shore up a fragile peace deal.

Implementing a peace deal since the end of a five-year civil war, in which an estimated three million people were killed, has proved difficult.