UNITED NATIONS, July 9 -- The UN Security Council on Thursday renewed its alarm at the 19-month-violence in South Sudan, calling for a comprehensive solution to the crisis in the world's youngest nation.

According to a press statement released here, the 15-member body expressed disappointment with the actions of President Salva Kiir and former Vice President Riek Machar Teny, saying "they have put their personal ambitions ahead of the good of their country and their people and jeopardized the foundation of this fledgling state."

The council said the failure of the two leaders to pursue peace has resulted in the death of tens of thousands of civilians, and that "there have been no signs that the parties are prepared to cease fighting and undertake a genuine peace process."

The statement came on the fourth anniversary of the independence of South Sudan, which was officially declared on July 9, 2011, following a referendum in which around 99 percent of the southerners voted for its secession from Sudan.

South Sudan's civil war and violence started in mid-December 2013. Political efforts so far have failed to bring an end to the conflict.

Recent weeks have seen an escalation of violence in Unity and Upper Nile states, with heavy fighting forcing tens of thousands of people to flee to bushes and swamplands, to areas that are difficult to reach.

In view of the grave situation, the most powerful UN body stressed the need to reinvigorate the political process to address the crisis, and reiterated its commitment to designating sanctions against political and military leaders that threaten the peace security and stability of South Sudan.