An overnight curfew has been imposed on Khartoum after Darfur rebels attacked a suburb of Sudan's capital Saturday, state television said. Heavy gunfire was heard in the west of Khartoum and helicopters and army vehicles headed towards the area, witnesses said. It is the closest the rebels have come to the centre of Khartoum. “We are announcing a curfew in the state of Khartoum from 5 p.m. (1400 GMT) until 6 a.m. starting from Saturday May 10th, 2008,” an army spokesman said on state television. Darfur rebels fought battles with Sudan's army in the North Kordofan province bordering Khartoum Friday and Saturday, according to a local government official and witnesses. A witness saw an attack helicopter and a convoy of 10 army trucks with machine guns attached on their way to Omdurman, a western suburb of Khartoum. Many in Khartoum hunkered down at home and the streets were filled by people rushing to their houses. Earlier, the Darfur Justice and Equality Movement (JEM) said it was strengthening its forces in Kordofan but not attacking government troops to avoid causing civilian casualties. But a local government official said the heavily armed rebels had scattered after an army counter-attack. Sudan tightened security in the capital late Thursday because of the fighting and the army accused Chad Saturday of backing the rebels. “The government and the armed Darfur movements are engaged in battles and there was bombing by planes and the rebels have scattered,” Abdel Majid Abdel Farid, a member of the administrative council of North Kordofan's eastern town of Hamrat Al-Wizz said. He said the Darfur rebels had spread out Friday all over the state in an “unprecedented manner” carrying heavy weapons.