UNITED NATIONS (AP) — The U.N. Security Council is expressing rare "horror" at the recent massacre of civilians in South Sudan and threatens sanctions.

The strongly worded press statement released Thursday deplores the killings last week in Bentiu, the capital of oil-producing Unity state, as well as the use of radio broadcasts to "foment hate and sexual violence."

The council statement also expresses "grave concern" over the more than 23,000 displaced people who are seeking shelter at the U.N. camp in Bentiu as the risk of a humanitarian crisis grows.

It also says council members "indicated their willingness to take additional measures," meaning sanctions, if attacks on civilians continue amid growing ethnic tensions.

The council statement calls on the government of the world's youngest nation to ensure the safety of civilians and denounce attacks.