On Sunday, the north's National Congress Party and the south's Sudan People's Liberation Movement announced the deal in Khartoum, following months of rising tension.
Party leaders say one law lays out the terms for the south's 2011 vote on independence. The others cover what is called a "consultation exercise" for people living in two north-south border regions, and a referendum on whether the oil-producing Abyei region will join the south.
Officials say they will show the agreement to their parties before releasing further details.
The vote on southern independence is a central part of a 2005 peace accord that ended Sudan's north-south civil war.
In the past, the two parties have accused each other of failing to implement the peace deal.
Last week, tensions flared again when three southern leaders were detained briefly after taking part in a protest outside parliament. Amnesty International says more than 200 people were arrested.
Leaders of the north and semi-autonomous south also have feuded over terms of Sudan's national elections, scheduled for April.
Analysts have warned that the tensions could undermine the 2005 peace agreement.
Some information for this report was provided by AFP and Reuters.