The Nigerian government said it plans to discuss with Boko Haram this coming week the terms for the release of more than 200 schoolgirls kidnapped by the militant group in April.
The two sides agreed to a cease-fire on Friday.
Top Nigerian presidential aide Hassan Tukur told VOA's Hausa news service that the militants have agreed in principle to free the schoolgirls, who were taken in Borno state.
Talks on the issue are expected to continue in Chad on Monday.
'Cautiously optimistic'
Turkur said negotiations in the past had not yet "yielded any positive results," but he is "cautiously optimistic" this time.
Boko Haram has not commented publicly on the developments.
Reports of new deadly attacks on Borno state villages Friday and Saturday raised speculation that the militant group was already violating the cease-fire. But Nigeria's government told VOA the cease-fire has not been broken.
A senior public affairs aide to the president, Doyin Okupe, told VOA that Boko Haram leadership is on board with the truce and that the violence was perpetrated by "fringe groups" of fighters who likely had not gotten word of the agreement.
A reporter working for VOA said at least 40 people were killed in the attacks.
Boko Haram has terrorized Nigeria for the last five years as it tries to turn northern Nigeria into a conservative Islamic state. Bombings, gun attacks and other acts of violence have killed thousands of civilians and police.
Kidnapped in April
In April, the militants outraged the world when they stormed a school in the remote northeastern village of Chibok, kidnapping about 270 girls. Fifty-seven managed to escape, but more than 200 are still being held.
Nigeria's highest-ranking military official, General Alex Badeh, announced the cease-fire agreement with Boko Haram on Friday. He ordered all of the country's military chiefs to abide by the deal.
The cease-fire talks were held in Chad and involved Chad's president, Idriss Deby, and senior officials from Cameroon.
Nigerian President Jonathan has been criticized at home and abroad for the inability of Nigerian troops to stop the the militants. But Tukur said the process has started and that the government will "go the extra mile" to solve the problem of Boko Haram.
VOA's Hausa news service contributed to this report.
