A high-level meeting to speed-up the peace process for Sudan's Darfur region has ended without a breakthrough in the Nigerian capital, Abuja.
President Obasanjo hosted the talks
African Union (AU) mediators said the talks had created a positive atmosphere and the Sudanese government and rebels had agreed to direct negotiations.
But a rebel spokesman said nothing new had come out of the meeting.
Negotiators will continue talks at a hotel in a bid to reach a deal before the end of April - the AU's deadline.
They have been negotiating for almost two years and progress has been agonisingly slow, the BBC's Alex Last reports from Abuja.
But mediators are optimistic that a new ceasefire deal could be agreed soon, possibly within days.
Millions still rely on food aid and emergency relief
They hope that would pave the way for a comprehensive peace agreement.
Since the conflict in Darfur began, tens of thousands have been killed and an estimated two million have been driven from their homes.
A ceasefire signed two years ago is often ignored, our correspondent adds, and it is questionable whether an agreement reached in Abuja could be implemented on the ground in Darfur.
Nigerian President Obasanjo and Republic of Congo President Denis Sassou-Nguesso, the AU's current chairman, were at the talks along with the Sudanese vice-president and Darfur rebel representatives.
"I can't say that there are any tangible results," Ahmed Tugod, chief negotiator for the Justice and Equality Movement rebel group, said afterwards.
"We are back to the stage of consultations between the parties and the mediation at the hotel."
However, AU mediator Salim Ahmed Salim told Reuters news agency the meeting had boosted the talks, creating the "right political conditions".