JUBA/KHARTOUM - At least 24 people have been killed in fresh fighting in the volatile borderland between Sudan and South Sudan, the southern army and rebels said on Saturday.

South Sudan's army spokesman Philip Aguer said his troops killed seven fighters from a militia supported by Khartoum which had crossed the poorly-defined border.

The South's army captured a Sudanese army truck used by the fighters during the skirmish in Obed in Upper Nile state in the northeast of the country, Aguer said.

Sudan's army spokesman Al-Sawarmi Khalid could not be reached on his mobile phone.

In separate violence on Sudan's side of the border, rebels from the Sudan People's Liberation Movement-North (SPLM-North) accused a militia from South Sudan, supported by Khartoum, of having attacked a village and killed 17 people.

The militia also wounded 35 civilians during their attack in the area of Abujibeha in oil-producing South Kordofan state, SPLM-North spokesman Arnu Lodi said.

Sudan and South Sudan came close to war in April, their worst fighting since southern secession in 2011 under a peace deal which ended decades of civil war.

Both countries agreed in September to end hostilities by withdrawing their armies from the disputed border and to resume cross-border oil exports. But neither side has implemented the agreement and the two countries accuse each other of backing rebels in their respective territories.

The African Union is next week hosting another round of talks between the neighbours aiming to set up a buffer zone, a precondition for Sudan to restart oil exports.

South Sudan shut down its output of 350,000 barrels day a year ago in a row with Khartoum over pipeline fees. Oil is vital to both countries' beleaguered economies.

The AU twice brought together Sudan's President Omar Hassan al-Bashir and his South Sudanese counterpart Salva Kiir in Ethiopia last month but there has been no sign of progress.