Burundi's government and the country's last active rebel group have agreed to end hostilities and draft a permanent ceasefire deal in the next two weeks.
The signing ceremony followed nearly three weeks of talks
But President Pierre Nkurunziza was only "half-satisfied" with the deal, having hoped to sign a full ceasefire.
Representatives of the government and the Hutu National Liberation Forces (FNL) rebels met in Tanzania on Sunday.
Observers say a deal with the FNL is seen as one of the final hurdles for stability after the long civil war.
"The government was ready and sure that it would sign a ceasefire agreement... He did not anticipate returning with an agreement of principle," presidential spokesperson Hafsa Mossi told reporters after they returned home on Sunday evening.
The truce follows nearly three weeks of talks mediated by South Africa.
The FNL is the only group still outside a power-sharing agreement aimed at ending the conflict.
Although the government and FNL rebels agreed a ceasefire in May last year, fighting between the sides resumed after only a week.
About 300,000 people have been killed in the civil war sparked in 1993 by the assassination of Burundi's first Hutu head of state and democratically-elected president, Melchior Ndadaye.
Reconstruction and development
"The parties commit to engage in serious discussions aimed at ending hostilities and to reach a comprehensive ceasefire within the period of two weeks," the agreement signed in Dar es Salaam by NFL leader Agathon Rwasa said, AFP news agency reported.
President Nkurunziza was present at the ceremony, along with the South African and Tanzanian presidents and representatives of the African Union and the United Nations.
Hundreds of thousands have fled the Burundi conflict over the years
The accord would pave the way for the FNL's return as a political party involved in post-conflict reconstruction and development, South African foreign affairs spokesman Ronnie Mamoepa was quoted as saying.
The signing was supposed to have taken place on Saturday, but officials were quoted as saying that technical problems caused a delay.
There are no details of how remaining disagreements have been overcome.
A government official had said that the earlier sticking point was a demand by the FNL for the national army to be disbanded.
The FNL was the only one of seven Hutu rebel groups not to sign a 2000 peace deal which saw a power-sharing government installed last year headed by Mr Nkurunziza, a former Hutu rebel leader.
The talks which began on 29 May were the FNL's first direct negotiations with the Burundi government since it was elected.
Tensions continued after the current round of talks began, and the government accused the FNL of shelling the capital Bujumbura.
However the rebels denied responsibility.