JUBA : UN Security Council envoys warned South Sudan's warring leaders Tuesday they would face sanctions if a civil war that has pushed the young nation to the brink of famine does not stop."The council has made it very clear: that it is prepared to impose consequences if there continue to be spoilers, if there continue to be people carrying out gross violations of human rights," US ambassador to the UN Samantha Power said after meeting with President Salva Kiir."We will not tolerate violation of the cessation of hostilities and people who spoil the peace agreement," Power told reporters, in one of the strongest warnings yet. "We have delivered that message here, and we will deliver it to Riek Machar," she added. Thousands of people have been killed and over 1.5 million have fled almost eight months of carnage sparked by a power struggle between Kiir and his sacked deputy Machar, with battles between government troops, mutinous soldiers and ragtag militia forces divided by tribe."The parties must know that the people of South Sudan have suffered enough," Rwandan ambassador Eugene-Richard Gasana told reporters.