United Nations peacekeepers have positioned armored personnel carriers and are patrolling an area in Sudan where units made up of Northern and Southern Sudanese troops clashed last week, killing 54 soldiers and wounding 85 others.

"The United Nations urges the parties to remain calm and exercise caution," spokesman Martin Nesirky told a news briefing in New York Tuesday, referring to the outbreak of violence in Malakal in Sudan's Upper Nile State between 3 and 5 February.

All movement restrictions at the Malakal airport, which was closed after the clashes, have been lifted, and it is now open for regular traffic, he said, adding that the situation is now relatively calm.

The clashes erupted before yesterday's announcement of the official results of January's independence referendum in South Sudan, showing that an overwhelming majority opted for secession from what until now has been Africa's largest country.

In a joint statement issued today, the UN joined a dozen signatories in hailing the official results, a culminating point of the 2005 Comprehensive Peace Agreement (CPA) ending two decades of civil war between the North and the South that killed some 2 million people and drove an estimated 4.5 million others from their homes.

As Secretary-General Ban Ki-moon and the panel he appointed to monitor the vote did yesterday, they called on both sides to reach lasting post-referendum arrangements on such issues as border security, citizenship, wealth-sharing, frontier demarcation, and popular consultations in the states of South Kordofan and Blue Nile. Also still to be decided is the issue of Abyei, an area straddling northern and southern Sudan, that was due to have voted in a separate but simultaneous referendum on which side it would join. But a referendum commission has yet to be established there, and there is still no agreement on who would be eligible to vote.

"We emphasize our commitment to the establishment of long-term peace, security and prosperity for all of the people of Sudan," the co-signatories said in the statement. "As witnesses to the CPA, we recognize the critical importance of continued close cooperation between the Northern and Southern Sudan and we underline our willingness to continue to provide international support."

The other signers were the African Union, Egypt, the European Union, the Intergovernmental Authority on Development, Kenya, Italy, the Arab League, Netherlands, Norway, Uganda, United Kingdom and United States.