The head of peacekeepers in the Darfur region of Sudan has warned of increased violence ahead of January's referendum on possible independence for the south.
Ibrahim Gambari condemned recent clashes between the Sudanese army and two Darfuri rebel groups.
Some analysts accuse the government of trying to eliminate the rebels before it deals with the referendum.
Mr Gambari says the renewed violence follows the two groups' refusal to take part in negotiations.
The rebel group are the Justice and Equality Movement and the Sudan Liberation Army-Abdul Wahid faction.
"Since they pulled out, and after the rains have stopped, there has been a resumption of the fighting in South Darfur as well as North Darfur, particularly in Jebel Marra East," Mr Gambari, head of Unamid, said.
South Sudan is likely to vote to split away from Sudan, which would dramatically alter the balance of power in the country.
If the south does go, the relative importance of the Darfur rebels could increase in a smaller country.
Equally, a return to north-south conflict is a real prospect, and Khartoum would not want to have to fight on two or more fronts.