A woman prepares food outside her temporary house at Konyo Konyo burial ground in Juba, capital of South Sudan, Nov. 5, 2017. (Xinhua/ Gale Julius)

JUBA, Dec. 14 (Xinhua) -- The UN High Commissioner for Refugees Filippo Grandi has appealed to warring parties to help settle conflict that entered its fourth year.

Grandi said Wednesday the devastating effects of the fighting were a direct consequence of failures in political leadership and called on all sides to put an end to deepening humanitarian crisis and Africa's largest refugee crisis.

"Urgent, concerted action by regional and international actors is needed before it is too late," Grandi stressed in a statement.

He said pressure must be brought to bear on those driving this deadly conflict, which has uprooted a third of South Sudan's people in just four years, and killed and maimed countless more.

"The world can not continue to stand by as the people of South Sudan are terrorized by a senseless war," he added.

The head of the UNHCR, who noted that 63 percent of all South Sudanese refugees are under 18, labelled the situation "a children's refugee crisis" as "many children are arriving unaccompanied, separated and deeply traumatized."

Grandi said the South Sudan conflict has created the largest refugee crisis on the African continent and estimated the refugee population to exceed 3 million by December 2018.

According to the UN, insecurity coupled with a failing economy continues to hamper food production and disrupt markets, leading to extremely high food prices.

Large sacks of staples such as sorghum, maize, and wheat flour have increased in price by up to 281 percent compared to last year, and were as high as 560 percent during May, the peak of the lean season.

Grandi called on the parties to the conflict to find a political solution, stressing that the success of the High Level Revitalization Forum in Ethiopia is key to ending the suffering of South Sudanese refugees and the killing of innocent civilians.

South Sudan descended into violence in December 2013 after political dispute between President Salva Kiir and his former deputy Riek Machar led to split within the Sudan's People's Liberation Army (SPLA), leaving soldiers to fight alongside ethnic lines.

A 2015 peace agreement to end the conflict was weakened after renewed fighting in July 2016 forced Machar to flee the country.