A deal to resolve a border dispute has been signed by the leaders of Angola and the Democratic Republic of Congo.
Signed during President Joseph Kabila's visit to Angola, it will return the boundaries to their colonial borders.
Angola's President Eduardo Dos Santos said the deal also tackles illegal immigration from DR Congo, which he says is a matter of national security.
Earlier this month, Angola reportedly expelled about 25,000 people from its mining areas to DR Congo.
The border area is rich in oil and diamonds.
Thousands of illegal diamond miners were deported from Angola in 2004, amid accusations of brutality.
Mr Dos Santos has said the borders needed to be clarified, as some people were using the issue to damage relations between Angola and DR Congo.
A team from the former colonial powers, Portugal and Belgium, will demarcate the border, which will be ratified by the African Union.
Correspondents say the two countries have experienced many years of war leading to confusion over their common boundary.