Nigeria's president has gone on national television and radio to reassure residents of an oil-rich peninsula being handed to Cameroon.
Many Bakassi residents say they do not want to live in Cameroon
President Olusegun Obasanjo told residents of the Bakassi peninsula their safety would be guaranteed even when Nigerian troops leave this year.
Mr Obasanjo agreed on Monday to implement a 2002 World Court ruling after talks at the United Nations.
A BBC correspondent said people in the area feel betrayed by the deal.
The territorial dispute sparked military clashes between Nigeria and Cameroon during the 1990s.
Most of those who live in Bakassi are Nigerians and are strongly opposed to coming under Cameroonian jurisdiction.
"We have ensured that Nigerians living now on the peninsula have a choice either to relocate or to remain in Bakassi," Mr Obasanjo said.
"Whichever choice they make, we have taken adequate measures for their protection, security, welfare and well-being. That was our concern and that we have achieved."
He also said that Cameroon had agreed to respect their culture, language, beliefs, property and fishing rights and not to impose "discriminatory" taxes.
Nigerian troops are to leave Bakassi within 60 days, with a possibility of extending this by a further 30 days, following the deal between Mr Obasanjo and Cameroon's President Paul Biya, brokered by UN Secretary General Kofi Annan.
A special transitional arrangement will be in place for five years, Mr Obasanjo said.
Following the deal, Mr Obasanjo said solving the dispute peacefully was far cheaper than war and said it could serve as a model for other African disputes.
Bakassi juts into the Gulf of Guinea - an area which may contain up to 10% of the world's oil and gas reserves.
It is also rich in fish.
Nigeria has always said it would abide by the 2002 ruling but in 2004 said that "technical difficulties" prevented it from handing over the peninsula.
The 2002 International Court of Justice ruling was based on a 1913 treaty between former colonial powers Britain and Germany.
The agreement also settles the border for 1,690km (1,056 miles) up to Lake Chad.
Some villages further north have already been exchanged.