South Sudan split away from Sudan last year under a 2005 peace deal that ended decades of civil war, but the two have remained at odds over a range of issues and conflict has continued to plague their borderlands.
One of the most contentious issues has been Khartoum's accusation that Juba is supporting the rebel Sudan People's Liberation Movement-North (SPLM-N) in South Kordofan and other insurgents. South Sudan denies the charge but diplomats say the accusations are credible.
Sudan's army said rebels had launched an attack against government forces in the Rashad area in the state's northeast on Thursday, SUNA said.
"The army repulsed this limited attack," army spokesman Al-Sawarmi Khalid told SUNA, adding that several civilians had been wounded when a car ran into a mine rebels had planted on a road near Rashad on Friday.
The SPLM-N was not immediately available for comment. Its spokesman said on Friday its forces had clashed with the army in the Rashad area on Wednesday.
Sudan and South Sudan are expected to resume negotiations over border security in Addis Ababa next week, talks delayed because of the funeral for Ethiopia's former Prime Minister Meles Zenawi.
The two countries are expected to come under pressure from mediators to reach a partial deal on border security so that they can resume oil exports vital to both economies.
Landlocked South Sudan shut down its oil output in January in a row with Khartoum over how much it should pay to export through Sudan.
The two sides reached an interim agreement on fees last month but Sudan says it wants a security deal before crude flows resume.
South Sudan seceded after voting overwhelmingly for independence in a 2011 referendum. Some 2 million people died in the decades-long war between north and south.
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