EDS NOTE GRAPHIC CONTENT In this image taken from video dead bodies lie on the road near Bentiu South Sudan on Sunday April 20, 2014. U.N.'s top humanitarian official in south Sudan Toby Lanzer told The Associated Press in a phone interview Tuesday April 23, 2014, that the ethnically targeted killings are "quite possibly a game-changer" for a conflict that has been raging since mid-December and that has exposed longstanding ethnic hostilities. There was also a disturbing echo of Rwanda, which is marking the 20th anniversary this month of its genocide that killed 1 million people. "It's the first time we're aware of that a local radio station was broadcasting hate messages encouraging people to engage in atrocities," said Lanzer, who was in Bentiu on Sunday and Monday. "And that really accelerates South Sudan's descent into an even more difficult situation from which it needs to extract itself." (AP Photo/Toby Lanzer, United Nations)

NAIROBI, Kenya - The U.N. Security Council on Wednesday viewed "horrific pictures of corpses" from the scene of last week's massacre in South Sudan and discussed taking actions that could include sanctions, diplomats said.

The U.N. has said hundreds of civilians were killed in the massacre last week in Bentiu, the capital of oil-producing Unity state. The top U.N. aid official in South Sudan, Toby Lanzer, has said "piles and piles" of bodies were left behind.

Security Council members watched a video showing bodies lining a street and the interior of a mosque where civilians had sought shelter from rebel forces taking control from government troops amid ethnic tensions in the world's newest country.

"Horrific pictures of corpses," France's ambassador to the U.N., Gerard Araud, tweeted from the meeting. "No place safe for refugees."

U.N. peacekeeping chief Herve Ladsous said the "cycle of violence must stop immediately" and warned that a "humanitarian catastrophe will become even more a certainty" if it doesn't.

Because of the months of fighting, more than 1 million people have fled their homes. With few residents tending crops, U.N. officials say the country faces a severe risk of famine in the months ahead.

Araud told reporters, "I think we are ready to go down the road of sanctions."

In a tweet after the meeting, U.S. Ambassador Samantha Power called for sanctions on "political spoilers and those who target civilians."

President Barack Obama earlier this month warned that the United States may levy sanctions, including visa bans and asset freezes, on individuals and entities involved in stoking violence in South Sudan.

The massacre has left diplomats and the U.N. mission in South Sudan questioning what to do next.

"We have also to face the fact that maybe we can't co-operate with this government anymore," Araud told reporters. "Because atrocities are committed by both sides. So I do think we have to have some soul-searching about what should the U.N. do."

Ladsous told the council that neither the South Sudan government nor the rebel forces is sincere in participating in peace talks, but the talks had to be supported as "the only game in town," according to a U.N. diplomat who spoke on condition of anonymity because the meeting was closed. An earlier cease-fire agreement between the sides didn't hold.

Violence has been raging in South Sudan since mid-December. Much of the fighting has been along ethnic lines, with supporters of the president, a Dinka, pitted against supporters of the former vice-president, a Nuer.

Human Rights Watch has called on the Security Council to investigate the killings in Bentiu and said the violence shows that ethnically motivated brutality against civilians is spiraling out of control in the landlocked country, which gained its independence from Sudan in 2011.

As tensions have risen, the U.N. mission has faced attack, even as tens of thousands of civilians continue to take shelter inside its bases across the country.

In a statement Wednesday, the mission said South Sudan Minister of Information Michael Lueth was wrong to tell a news conference that residents seeking protection were barred from entering the U.N. camp near the Bentiu massacre scene.

The mission said the numbers of people sheltering inside the base rose from 8,000 on April 15, when the killings started, to about 22,500 by Wednesday.

The U.N. also said Lueth was wrong to suggest that refugees were rebel fighters or sympathizers, and these remarks could encourage attacks on refugees inside U.N. camps.

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Anna reported from the United Nations. Associated Press writer Edith M. Lederer at the United Nations contributed.

News from © The Associated Press, 2014