UN chief Ban Ki-moon on Wednesday commended efforts by the governments of Sudan and South Sudan to make progress in tense post-independence talks.

Ban said the agreements on borders and citizenship were "an important step forward and an encouraging manifestation of both parties' spirit of cooperation and partnership."

The Secretary-General also said in a statement he welcomed a planned summit between the leaders of both countries to sign both agreements, "and encourages them to resolve all other outstanding matters as a matter of urgency."

South Sudan said earlier Wednesday said relations with its former civil war foe had become "positive."

The newly-independent nation had previously accused Sudan of "stealing" oil during negotiations to resolve issues such as oil revenues and contested territory, leading to fears of a renewed war.

South Sudan's top negotiator Pagan Amum told reporters the two nations inked deals to safeguard the status of each other's citizens and demarcate the oil-rich border, ahead of an April 8 deadline for southerners to leave Sudan.

The presidents of both countries are due to meet in the southern capital Juba soon to finalize the current deals and attempt to make progress on others, he added.

South Sudan split from the north in July with 75 percent of the country's crude oil, but relies on a pipeline, refineries and port in Sudan to export it.