President Barack Obama on Thursday warned the South Sudan government and rebel leaders that they may be slapped with US sanctions if they fail to make peace.

Mr Obama signed an executive order clearing the way for possible bans on travel to the US and financial penalties for South Sudanese who continue to stoke violence.

A White House statement said the president's action “sends a clear message: Those who threaten the peace, security, or stability of South Sudan, obstruct the peace process, target UN peacekeepers, or are responsible for human rights abuses and atrocities will not have a friend in the United States and run the risk of sanctions.”

“Both the government of South Sudan and Riek Machar’s rebels must immediately engage in and follow through on the inclusive peace process led by the Intergovernmental Authority on Development and resolve this conflict,” the White House added.

“The people of South Sudan are calling for peace. There is no room for excuses or delay.”

Mr Obama's warning reflects US frustration and disappointment over the breakdown of a state that Washington helped lead toward independence.

READ: US issues stern warning on South Sudan conflict

The US has provided hundreds of millions of dollars in aid to South Sudan in the four years since its people voted to establish a nation.

South Sudanese “expected their leaders to act with courage and conviction, to put the interests of the people first, and to be statesmen, not strongmen,” the White House declared.

“The United States will not stand by as those entrusted with South Sudan’s future put their own interests above those of their people.”

US officials indicated on Thursday that the European Union and the UN Security Council are considering action similar to that taken by Mr Obama.