ADDIS ABABA: The rival leaders of Sudan and South Sudan arrived in Ethiopia Friday to push for progress on stalled economic, oil and security deals between the former civil war foes, officials said.

The summit between Sudanese President Omar al-Bashir and his Southern counterpart Salva Kiir comes despite accusations from Juba on Thursday that Khartoum had launched air and ground attacks inside South Sudan.

"Both leaders have arrived," Ethiopian foreign affairs spokesman Dina Mufti told AFP, adding that they were expected to meet face-to-face later.

However, Bashir and Kiir first met separately with Ethiopian Prime Minister Hailemariam Desalegn and African Union mediator Thabo Mbeki, the former South African president, according to diplomats and an AFP reporter.

It was not immediately clear when the presidents would hold talks directly.

The summit of the leaders, whose nations are both struggling with economic austerity cuts following Juba's halting of oil exports through Sudan's pipelines, is the latest of repeated rounds of AU-mediated talks.

AU chief Nkosazana Dlamini-Zuma said she hoped the summit would "enable the two presidents to agree on the best means and ways of overcoming the challenges" of implementing deals inked in September.

Juba has accused Khartoum of a series of attacks -- regularly dismissed by Sudan -- ever since the two nations came close to all-out war in March and April last year, when their armies fought bitter battles over their disputed frontier.

But the fresh claims of clashes will add to tensions between the presidents, who will meet for the first summit since they signed security and oil agreements three months ago that are still not implemented.

The United States, Britain and Norway issued a joint statement ahead of the talks calling for a settlement, urging for the armies of both nations to "immediately withdraw" from their frontier.

The resumption of oil production would be "particularly valuable for both economies and should not be held up by negotiation on other issues", they added.

Along with a demilitarised border buffer zone, the September pacts allowed for a resumption of South Sudanese oil exports through Sudan. They also said border points would be reopened for general trade.

The meeting is also hoped to "find solutions to the pending issues of the Abyei area", a flashpoint Lebanon-sized region claimed by both Khartoum and Juba, Dlamini-Zuma added in a statement.

The AU has proposed that if a deal is not struck on Abyei, the matter would be referred to the United Nations Security Council for resolution.

However, Sudanese Foreign Minister Ali Karti said that referring Abyei to the UN would "not help bring about peace", according to the Sudanese Media Center, which is close to the security services.

South Sudan said it was committed to the talks, despite accusations of ground and air attacks in remote South Sudanese border regions on Wednesday, claims unconfirmed by UN peacekeepers.

"This summit is important because we want to ensure the full implementation of the agreements we have already signed," South Sudan's Information Minister Barnaba Marial Benjamin said.

Sudan has made no comment on the reported clashes, but the state-run SUNA news agency said Bashir would meet with Kiir "to speed up implementation of the cooperation agreements".

South Sudan separated from Sudan in July 2011 under a peace agreement that ended a 1983-2005 civil war, but key issues including the demarcation of hotly contested border zones remain unresolved.

Khartoum also accuses South Sudan of supporting rebels operating in Sudan, which has been a major obstacle to implementing the agreements.

The South, in turn, says Sudan backs insurgents on its territory, a tactic it used to deadly effect during the two decades of civil war.