The top UN official in Sudan has met members of the former southern rebel movement to discuss its recent decision to withdraw from the unity government.

The announcement by the Sudan People's Liberation Movement (SPLM) had raised fears that a 2005 truce might collapse.

UN representative Taye-Brook Zerihoun said he was encouraged to hear the SPLM would continue dialogue with the ruling National Congress Party (NCP).

The 2005 deal ended a 21-year war between government and southern rebels.

In terms of the deal, known as the Comprehensive Peace Agreement, the SPLM controls the southern regional government and participates in the national government in Khartoum.

The UN is concerned that the withdrawal of the SPLM from the national unity government could threaten talks scheduled in Libya for the end of the month over the crisis in Darfur.

Consultations

United Nations Mission in Sudan (Unmis) spokeswoman Radia Achouri said Mr Zerihoun was "encouraged" by the talks after the SPLM "stated the government of the south will remain engaged in discussions and consultations with their partners [in the north]" .

Mr Zerihoun travelled to Juba, the capital of southern Sudan, to meet SPLM representatives, including leader Salva Kiir.

He is expected to hold talks with NCP representatives in the coming days, Ms Achouri said.

The US has called on the ruling parties of north and south Sudan to exercise restraint after the ex-southern rebels withdrew from the unity government.

The BBC's Amber Henshaw in Khartoum says the peace deal has been looking increasingly fragile over the last few weeks as important deadlines have been missed.

The SPLM wants boundary demarcations, the redeployment of northern troops from the south to be implemented and the chance to reshuffle its ministers in the unity administration.

Some 1.5 million people died in the conflict - Africa's longest civil war - which pitted the mainly Muslim north against the Animist and Christian south before the CPA was agreed.

There are currently 10,000 UN peacekeepers in southern Sudan.

PHOTO CAPTION

Protest in September in Juba about the CPA