There can be no military solution to tensions between Sudan and neighbouring South Sudan, the British embassy in Khartoum said on Wednesday, after a reinforcement of forces along the border.

The embassy said it welcomed a memorandum on non-aggression and cooperation signed between Juba and Khartoum last Friday.

But it expressed "grave concern at the recent build-up of forces and escalation of tensions in conflict-affected border areas."

The embassy urged both governments to fully respect the provisions of the memorandum.

"There can be no military solution. It is vital to pursue peace and to avoid further unnecessary suffering for civilians," the embassy said in a statement.

The memorandum -- signed in Addis Ababa by intelligence chiefs of the two nations -- calls for "respect for each other's sovereignty and territorial integrity" and says they will "refrain from launching any attack, including bombardment."

Juba's military said the agreement was broken two days later when Sudanese warplanes bombed a disputed frontier area, wounding four Southern soldiers.

UN Secretary General Ban Ki-moon warned last week that tensions between Sudan and the breakaway South could escalate if outstanding issues are not resolved.
South Sudan split from Sudan in July after an overwhelming vote that followed more than two decades of war that killed some two million people.

At around that time, fighting broke out in South Kordofan and nearby Blue Nile state between the government and ethnic minority insurgents who fought alongside the former rebels now ruling South Sudan.

More than 140,000 Sudanese refugees have fled to South Sudan or Ethiopia since the fighting began, according to the United Nations.

On Tuesday the UN Security Council expressed "deep and growing alarm" over rising levels of malnutrition and food insecurity in parts of South Kordofan and Blue Nile.

The statement called upon Khartoum "to allow immediate access to UN personnel, including access to conduct a needs assessment."

Sudan has cited security concerns in severely restricting foreign aid organisations in the war zone.

During the latest round of talks between Sudan and South Sudan in the Ethiopian capital, they again failed to agree on compensation for southern oil flowing through the north's infrastructure, a major unresolved sticking point, post-separation.

South Sudan took three quarters of Sudan's oil when it gained independence, but all pipeline and export facilities are controlled by the north.