Discrimination against non-Muslims was a major reason why South Sudan seceded in 2011
A powerful rebel group in Sudan has signed a declaration of principles with the government - raising hopes that it will eventually sign a peace agreement.
The SPLM-North Abdelaziz al Hilu faction was a notable absentee when other rebel groups signed a peace deal this week.
But the group's leader Abdelaziz al Hilu carried on talking with the government - and late on Thursday put his signature to a declaration of principles.
He appears to have won a significant concession from the government - the confirmation that the constitution should be based on the separation of religion and state, and in the absence of this the right to self-determination should be respected.
Sharia law was introduced in Sudan in 1983, and ever since the country became independent 60 years ago, non-Muslim minorities have been discriminated against.
This was a major reason why South Sudan seceded in 2011.
In addition, the declaration of principles allows Mr Abdelaziz's forces to keep their weapons and their capacity to protect the areas they control.
