Story highlights President Salva Kiir is embroiled in a power struggle with his fired deputy

The conflict has raged for nearly a year despite previous ceasefire deals

United Nations: More than 1.5 million people have been displaced

Regional leaders on Saturday warned South Sudan's warring rivals to end their months of conflict or risk intervention by neighboring nations to restore peace.

President Salva Kiir has been embroiled in a power struggle with his fired deputy, Riek Machar, whom he accused of trying to oust him through a coup last year.

Since the attempted coup in December, militia loyal to both have battled each others' forces. Violence has quickly spread, with reports of mass killings nationwide.

Talks and repeated pleas for peace have yielded no results.

IGAD, a regional African bloc that comprises neighboring nations, has given the two sides 15 days to consult and come up with a resolution.

Both sides must talk and produce a plan for an "unconditional, complete and immediate end" to all violence, it said.

Any side that violates the resolution will face region-wide asset freezes, travel bans and an arms embargo, among other sanctions, the regional bloc said in a statement.

"The IGAD region shall, without further reference to the warring parties, take the necessary measures to directly intervene in South Sudan to protect life and restore peace and stability," it said.

The conflict has continued unabated for nearly a year, raising fears it may spill into neighboring nations already taking in refugees fleeing the violence.

More than 1.5 million people have been displaced, according to the United Nations, and thousands more killed. Some civilians have fled to U.N. bases in the country, making the facilities targets for armed militants.

South Sudan seceded from Sudan in 2011 after decades of war, making it the world's youngest nation.

Since the split, the nation has battled various setbacks, prompting IGAD nations, including Kenya, Ethiopia, Sudan and Uganda, to seek mediation. The violence is divided along tribal lines -- the Nuer community backs rebel leader Machar while the President is a Dinka.

This would not be the first deal between the warring parties. Both the government and rebels signed a ceasefire deal earlier this year, which did nothing to stop the bloodshed.

It called for an immediate end to all violence and military operations, but the fighting raged on.