A Bangladeshi Navy peacekeeper from the United Nations Mission in South Sudan looks at a World Food Program barge while patrolling on the white Nile near the town of Malakal, in the Upper Nile state of South Sudan, Sept. 8, 2018. (REUTERS Photo)

UNITED NATIONS, Sept. 18 (Xinhua) -- UN Under-Secretary-General for Peacekeeping Operations Jean-Pierre Lacroix said Tuesday that South Sudanese parties face daunting challenges in implementing a new peace agreement.

The deal signed on Wednesday by South Sudanese President Salva Kiir and rebel leader Riek Machar is an important milestone as it provides a roadmap for peace through reform, political transformation, security, socio-economic development, and national reconciliation, Lacroix told the Security Council in a briefing.

"Indeed, all the ingredients for success are present. However, there are legitimate questions and concerns about the commitment of the parties, and many practical aspects related to the implementation of the agreement still require clarification," he cautioned.

The onus of ensuring implementation of the agreement will be on the parties, he said. It will be crucial for the parties to build trust and muster the political will to work together to ensure a more protective environment that will allow all South Sudanese stakeholders to meaningfully engage in the full implementation of the agreement, said Lacroix.

A full and immediate cessation of hostilities is an imperative first step."

However, he said that there have been reports of fighting in parts of the country within days of the signing of the agreement.

"We remain concerned about the potential for further clashes where government and opposition forces are in close proximity," he said.

The fighting has worsened the already dire humanitarian and human rights situation in the country, said the UN peacekeeping chief.

Extreme violence, including conflict-related sexual violence, and threats and harassment experienced by civilians continue to be a hallmark of the five-year-old conflict, he said.

"Despite the concerns, the need for peace in South Sudan is so urgent that we must seize this opportunity and work together to make the agreement a basis for lasting peace," said Lacroix.

Shortly after its independence from Sudan in 2011, South Sudan plunged into civil war. Up to 300,000 people are estimated to have been killed since late 2013. Some 1.8 million people are displaced within South Sudan, 2.5 million others have fled to neighboring countries.