South Sudan has accused Sudan of bombing and shelling areas on the southern side of their disputed border, calling the acts a violation of a UN-backed ceasefire which should have begun on Saturday.
Kella Dual Kueth, a South Sudan military spokesman, said there were attacks on Monday and Tuesday in the states of Upper Nile, Unity and Northern Bahr el-Ghazal.
"Automatically this is a violation [of the ceasefire], Kueth said. "If we have a compromise and we are at peace and then I go and knife you in the back, what does that mean?"
He said he was not aware of any attacks on Wednesday.
Khartoum has repeatedly denied it is carrying out a bombing campaign over southern territory, saying instead it is the victim of its southern neighbour's aggression.
The latest allegations indicated that continuing tensions between the two neighbours, which erupted into border fighting last month, could hamper international efforts to push them to resume negotiations on various outstanding disputes.
Addressing Sudanese parliamentarians on Wednesday, Ali Ahmed Karti, Sudan's foreign minister, said Khartoum would co-operate with a UN Security Council resolution which called on both sides to commit to an African Union (AU) peace roadmap.
|In-depth coverage of North-South strife over border
"We ... will stick to the Security Council resolution ... Why be afraid of dealing with the Security Council resolution?
Dealing with it positively gives a chance for our friends to defend us," Karti said.
Disputes over oil exports, border demarcation and citizenship, arising from the South's secession as an
independent nation last year, led to direct clashes between the former civil war foes in April.
As the conflict escalated, the UN condemned Sudanese air raids on South Sudan's territory and international pressure forced South Sudanese forces to withdraw from the oil-rich area of Heglig which they had occupied.
The fighting prompted the Security Council to pass a resolution last week threatening sanctions if the two sides did
not follow the AU roadmap, which stipulates a ceasefire and a return to negotiations.
Both sides have made statements warily accepting the proposed peace plan but say they reserve the right to defend themselves if attacked.