South Sudan's ruling party accused northern authorities yesterday of arming rebels since the region's landmark independence vote last month, including renegade troops behind clashes that killed more than 200 people last week.
Pagan Amum, secretary general of the Sudan People's Liberation Movement (SPLM), said renegade southern general George Athor had received supplies from Khartoum since the January referendum in which the south voted to break away.
"Supplies were brought to George Athor even after the referendum, and this definitely must stop," Amum said.
The north has rejected similar accusations in the past.
Athor's forces launched a string of attacks on southern troops last week, which sparked clashes in which more than 200 people died, the majority of them civilians.
Southern officials described what happened in Jonglei, the region's most populous state, as a "massacre."
An official communique released by Amum following a five-day meeting of the SPLM's top leadership directly accused Khartoum's ruling National Congress Party and the northern army, the Sudan Armed Forces, of backing militia groups.
The party called on the NCP and SAF "to immediately disengage from sponsoring and reinforcing insurgency groups in the south."
"This is not in the interests of peace, and of good neighbourly relations between the people of north and south, and the overall security in the region," the statement added.
The attacks by Athor's men came just days after formal confirmation of the referendum results, in which almost 99 per cent of southerners voted to partition Africa's largest country.
Relations between north and south seemed to have improved during the referendum, but Amum's comments suggested a return to the war of words between the two sides which had sparked international concern last year.