The south’s dominant Sudan People’s Liberation Movement (SPLM) and the northern National Congress Party (NCP) have been at loggerheads over arrangements for the referendum and other looming votes, all promised as part of a 2005 accord that ended more than two decades of north-south civil war. “We have reached agreement on three very important laws which have been the grounds for serious disagreements between the two parties,” SPLM secretary general Pagan Amum told reporters. Amum said the laws would set out the terms of the southern referendum, a separate ballot on whether the oil-producing region of Abyei should join the south, and vaguer consultation exercises for the populations of the border regions of Blue Nile and Southern Kordofan.

The NCP and the SPLM, who fought each other during the civil war, joined a national coalition government under the 2005 Comprehensive Peace Agreement. But relations between the partners have been strained, most recently last week when Khartoum authorities arrested two senior SPLM officials and scores of their supporters during a protest. Analysts have warned of a risk of a return to conflict if the parties could not agree on the new legislation before national elections due in April, and the southern referendum in January 2011.

The referendum is one of the most divisive issues on Sudan’s political calendar. Many southerners, embittered by years of bloodshed, are thought to favour independence. But a vote for secession would mean Khartoum would lose control of most of the country’s proven oil reserves, predominantly found in the south. Sunday’s move was hailed as “an important breakthrough” by Derek Plumbly, chairman of the Assessment and Evaluation Commission that monitors the north-south peace deal. “But there is still a lot of work to do … a year is a short time,” he told Reuters, saying Sudan still had to appoint a referendum commission ahead of the 2011 vote.

Amum spoke at the end of four days of negotiations between Sudan’s President Omar Hassan al-Bashir, who heads the NCP, and south Sudan’s president and SPLM leader Salva Kiir. NCP official Nafie Ali Nafie also confirmed a deal on those issues had been reached during the meeting. Amum said the two sides also agreed to form a committee to discuss remaining issues, including arrangements for national elections and differences over a security bill which the SPLM has argued gives too many powers to security services. The parties have announced breakthroughs before that failed to end long term wrangling over the details of the peace accord.