The chief mediator in the Burundian peace process has said he cannot heal the deep rift between the government and the country's last active rebel group, the National Liberation Forces (FNL).
"The two parties agree on a number of issues, but there is big disagreement between the government and the FNL on two crucial aspects," said Defence Minister Charles Nqakula after holding a lengthy discussion between both sides.
These include the government's recognition of the rebels' political branch as a political party and allowing its members to enter the government, Nqakula said.
The government has refused to accept the FNL as a party with the name "Palipehutu", which means "party for the liberation of the Hutu people", arguing the constitution forbids parties with ethnic affiliations.
"We cannot resolve these political differences without the help of the region's leaders," he added.
Long-term facilitator Nqakula was reappointed earlier this month by Burundi's President Pierre Nkurunziza to help prevent a return to armed conflict.
Nqakula was due to head to Kampala to meet with other Burundi mediators, including Ugandan President Yoweri Museveni and his Tanzanian counterpart Jakaya Kikwete.
Burundi is struggling to emerge from the ashes of a civil war which erupted in 1993 and killed about 300 000 people.
The FNL signed a peace agreement with the government two years ago, but its implementation has been fraught with obstacles over how to share political and military power.