KHARTOUM, March 28 (Xinhua) -- The United Nations said Wednesday thousands of South Sudanese returning to their homeland from Sudan were stranded at Higlig area which is witnessing armed clashes between Sudan and South Sudan armies.

"A large government-organized convoy of approximately 1,700 people of South Sudanese origin returning to South Sudan was unable to continue beyond Higlig due to an upsurge of fighting in the area," UN Resident and Humanitarian Coordinator in Sudan Ali Al-Za'tari said in a statement a copy of which was obtained by Xinhua Wednesday.

"Most of the convoy has returned to Karasana, north of Higlig, but there are reports that some separated passengers remain in Higlig and are in urgent need of food, water and shelter," he added.

"There is an urgent need to ensure the safety and wellbeing of all of the returnees in the convoy," the UN official said, expressing concern about the recent armed clashes in the Higlig area of South Kordofan.

The United Nations is liaising with Sudanese government officials and has offered its assistance, said the statement.

Armed clashes have recently erupted between Sudan and South Sudan armies at Higlig, Sudan's most prominent oil fields area.

Sudan and South Sudan have failed to demarcate their joint border and dispute over many border areas including Jao which witnessed armed clashes on Feb. 26 in addition to the Abyei area.

Sudan and South Sudan on Feb. 10 signed a "Non-aggression Deal" to avoid an armed conflict between the two sides.

The agreement, reached under the African Union mediation in Addis Ababa, stipulated that each side should respect the sovereignty and territorial integrity of the other, not to intervene in the other's internal affairs, refrain from use of force and observe common interests and peaceful co-existence.