Human rights groups are urging the United Nations Security Council to place an immediate arms embargo on South Sudan in order to reduce unlawful attacks on civilians.

Such a ban would send a strong message that international community will not enable fighters who have shown a complete disregard for the laws of war, 30 human rights groups including Oxfam, Amnesty International and Human Rights Watch said in a letter sent Thursday.

The Security Council is considering a request from Secretary-General Ban Ki-moon to place an arms embargo on South Sudan and to ratchet up sanctions on individuals accused of hindering the peace process.

The letter points out that during five days of fighting between forces loyal to the president and the vice president, civilian neighborhoods and U.N. compounds were shelled.