Direct talks between military rulers and protest leaders have resumed in Sudan with some progress being made on the release of political prisoners, a mediator has said.

The negotiations had stalled since May due to disagreements over the composition of the top body that will lead the country during a transition period.

The African Union and Ethiopian mediators hope the two sides will agree on how to share positions on the sovereign council.

The opposition groups also want the deadly raid on their sit-in last month investigated.

The resumption of dialogue restores hopes for a transition to civilian rule.

After a first round of fresh talks on Wednesday, the African Union mediator said Sudan's military rulers had agreed to release all political prisoners. He did not offer further details or specify how many people were affected.

The military council, which is currently running Sudan, has been under pressure from the international community to hand over power.

Protests were held on Sunday across the country to press for change. The demonstrations were organised in spite of a month-long internet shut down and threats against opposition leaders.

By the time the talks collapsed in May, the two sides had agreed to have a majority civilian legislature and a three-year transitional period.