The presidents of Nigeria and Cameroon have failed to make significant progress in five hours of talks on the disputed oil-rich Bakassi area.
Many Bakassi residents say they are Nigerian
The leaders failed to agree a timetable for Nigerian troops to withdraw or on when to demarcate the maritime border.
The International Court of Justice awarded the peninsula to Cameroon in 2002, but Nigerian forces failed to pull out last September as planned.
Presidents Olusegun Obasanjo and Paul Biya met UN chief Kofi Annan in Geneva.
A spokesman for the Secretary General said this kind of diplomacy took time, and that the alternatives were certainly worse.
Mr Annan said he would be involved in working out and agreeing a new programme of withdrawal of the Nigerian troops.
Cameroon's President Biya said he thought progress was being made.
"We are heading to a definite solution to the problem," he said.
The two countries began marking out their common border earlier this year.
Bakassi juts into the Gulf of Guinea - which it is thought could contain up to 10% of the world's oil and gas reserves - south of the border between the two countries. It is also rich in fish.