South Sudan's leader Salva Kiir has met the president in an effort to resolve a crisis that has threatened to tear the country apart.
Mr Kiir is also the country's national vice-president
There was no comment on what they had discussed and further talks are due to take place on Monday.
Mr Kiir's ex-rebel group withdrew its ministers from government last week saying elements of a 2005 north-south peace pact were being ignored.
President Omar al-Bashir agreed in part to a request for a cabinet reshuffle.
But border demarcations and redeploying northern troops from the south are some of the things yet to be implemented.
The BBC's Amber Henshaw in the capital, Khartoum, says tensions have been brewing for months between the southern Sudan People's Liberation Movement (SPLM) and the governing National Congress Party.
The two signed the Comprehensive Peace Agreement (CPA) two years ago that ended the 21-year civil war.
Under the CPA, the SPLM controls the southern regional government and participates in the national government in Khartoum.
But the enemies in war have struggled to become partners in peace, our reporter says.
Mr Kiir - who is also the country's national vice-president - is travelling to Khartoum for the meeting.
Mr Bashir has been considering the SPLM's requests since Sunday
Our correspondent says it is hoped the men can stop the crisis from escalating further.
On Wednesday, Mr Bashir reshuffled his cabinet removing Lam Akol as foreign minister.
Mr Akol, although a southerner, was seen as too close to the NCP.
But the SPLM says not all their suggestions for ministers from the south were agreed to.
After meeting Mr Bashir on Tuesday, south Sudan Vice-President Riak Machar told the BBC that parts of the CPA that had not been implemented included:
- The redeployment of northern troops from the south, especially from Unity and Upper Nile states
- Issues of oil management and marketing
- The final border demarcation which means the division of oil wealth cannot be completed
- Issues to pave the way for a census in 2011, when the south could decide to split from the north.
Mr Riak said the north had until 9 January 2008, the third anniversary of the signing of the CPA, to resolve these issues.
Some 1.5m people died in Sudan's conflict - Africa's longest civil war - which pitted the mainly Muslim north against the Animist and Christian south before the CPA was agreed.