South Kordofan unrest: Sudan 'kills hundreds' of rebels
The rebels have not commented on the claims but previously accused the army of "ethnic cleansing" in the oil-rich area.
The state borders South Sudan, which became independent in July.
"Hundreds of soldiers from the Sudan People's Liberation Movement (SPLM-North) were killed during an attack on the city of Teludi this morning," Mr Haroun said.
Mr Haroun is indicted by the International Criminal Court for alleged war crimes in Darfur, where he was once the governor.
'Three fronts' Sudanese army spokesman, Sawarmi Khaled Saad, said more than 700 rebels attacked Teludi, east of the state capital Kadugli, the AFP news agency reports.
"The armed forces waited for the invaders to arrive on three fronts with equipment and on several vehicles, but in an hour the armed forces and popular defence forces beat back the attack, causing heavy losses," he is quoted by AFP as saying.
South Kordofan is one of three border areas - along with Abyei and Blue Nile - to have been affected by conflict since South Sudan became independent.
Sudan lodged a complaint with the UN Security Council in August, accusing South Sudan of backing the rebels.
The SPLM, in power in South Sudan, denies Khartoum's claims, even though it fought alongside the northern rebels during Sudan's decades-long civil war.
Sudan agreed to give the south independence in July, but held on to South Kordofan, Abyei and Blue Nile states.
Tens of thousands of people have fled their homes because of fighting in the three states.