UNITED NATIONS, Nov. 21-- A senior UN relief official on Friday concluded her three-day mission to South Sudan, calling on all parties to the conflict to respect their ceasefire commitments and urging the international community to continue providing support to enable humanitarians to scale up and expand critical aid operations, UN spokesman Stephane Dujarric told reporters here.

Kyung-Wha Kang, the UN assistant secretary-general for humanitarian affairs, said: "The level of violence experienced by civilians in South Sudan has been devastating. I was here a year ago and I am heartbroken to see that the promising young country that I saw is suffering so greatly."

"The scale of the needs is great," she said. "However much we scale up our operations, we will never be able to do enough if the conflict continues to destroy lives and livelihoods. All parties to the conflict must show leadership and bring peace to this country."

During her visit, Kang visited communities affected by the crisis in Juba and Jonglei State. She met with government representatives and humanitarian partners to discuss ways of improving access and strengthening protection of civilians, Dujarric said.

She urged parties to respect international humanitarian and human rights laws that clearly call for the protection of civilians and unhindered humanitarian access to people in need.

The year-long conflict in the world's youngest country has been brutal, the UN Office for the Coordination of Humanitarian Affairs (OCHA) said in a press release on Friday, adding that civilians have been killed, raped and beaten; homes torched; lives ruined.

Fighting has destroyed communities and separated families. More than 1.9 million people have fled their homes. More than 100,000 people have sought refuge in UN bases. Millions more fled into the bush and remain too fearful to return home or settle elsewhere.

Despite the extremely difficult situation for aid workers, who face active hostilities, access and logistical challenges, as well as threats to their own lives, the United Nations humanitarian agencies and partners have reached more than 3.5 million people with assistance this year, helped avert famine, and brought under control a deadly cholera outbreak, OCHA said. "However, the situation remains bleak and the number of people who are severely food insecure is projected to increase to 2.5 million people in early 2015."

Aid agencies are planning for next year, and are urgently calling for 600 million U.S. dollars by February to kick-start next year's operations. "In the dry season, we need to pre- position life-saving and livelihood supplies to reach all people in need, and carry out key repairs to roads and airstrips so that we can scale up and expand the aid operation," noted Kang.

Political in-fighting between South Sudanese President Salva Kiir and his former deputy, Riek Machar, started in December 2013 and subsequently turned into a full-fledged conflict.

The violence has left thousands of people dead and more than 1. 8 million displaced, according to the United Nations. Recently, fighting has resumed in Upper Nile and Unity states, causing fear that the humanitarian crisis would be magnified.