The FNL quit a joint ceasefire monitoring team last month, saying government troops had not withdrawn from areas under their control, which was one of the terms of a truce signed in September.
Although both parties say they are ready for discussions, they have yet to agree on when and where they should take place.
"I came here to see how we can remove the obstacles that seem to be blocking the implementation of the ceasefire agreement," said South African mediator Charles Nqakula, who held talks with Burundian President Pierre Nkurunziza.
Nqakula said he planned go to Dar Es Salaam, Tanzania, to meet FNL leaders and give a report to regional leaders who will then decide on the date and the venue of the meeting.
The FNL fear for the security of their leaders in the Burundi capital Bujumbura.
Nkurunziza has said the government is flexible on the location, saying it could be outside of Burundi, but criticised the FNL for "changing its mind all the time".
The FNL is demanding new negotiations on their integration into the country's institutions and a clear understanding of what role they will play in the nation's armed forces.
The peace agreement between Nkurunziza and the FNL stirred hopes of lasting peace in the coffee-growing nation after more than a decade of ethnic civil war that killed 300,000 people.
But the FNL's persistent insurgency is seen as a final barrier to stability in the landlocked country of 7 million.
- Reuters - Thomson Reuters Foundation
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