South Sudan has started withdrawing its army from the border with Sudan to set up a buffer zone between the African neighbors, the government said on Thursday.

The withdrawal would be completed by 4 February, the government in Juba said in a statement, adding that it expected Sudan to do the same in what would be a step forward in efforts to cool tensions between the neighbors.

"By withdrawing its forces ... the government of South Sudan is clearly demonstrating its full compliance with the signed security agreements and full commitment to their implementation," the statement said.

There was no immediate comment from Sudan.

The neighbors came close to war in April in the worst border clashes since South Sudan declared independence from Sudan in 2011.

After mediation from the African Union, both agreed in September to resume oil exports from the landlocked South through Sudan, a lifeline for both struggling economies.

But mutual distrust remains deep and neither side had yet withdrawn its armies from the border, a condition for both to restart oil flows.

Security officials from both countries are currently holding talks in Addis Ababa to discuss practical steps to set up a buffer zone along the disputed border.

The deal has been complicated by fighting on the Sudanese side of the boundary between Sudan's army and SPLM-North rebels who have vowed to topple Bashir.

Khartoum say South Sudan supports the insurgents. Juba denies that and says Sudan is backing militias in its territory.

South Sudan became independent in July 2011 under a peace agreement which ended decades of civil war fuelled by ideology, oil, ethnicity and religion.