African-brokered crisis talks between Sudan and South Sudan after days of border clashes were delayed Thursday, March 29 but the rival sides pledged to stop an escalation into full-blown war, AFP reported.

The talks in the Ethiopian capital were likely to be deferred because chief mediator, former South African president Thabo Mbeki, could only reach Addis Ababa on Saturday, South Sudan's top negotiator told AFP.

Pagan Amum has said aim was to "pursue peace" and to stop the recent violence, including airstrikes and tank battles, from "spreading to a full fledged war."

Sudanese foreign affairs official Rahamatalla Mohamed Osman was already in Addis Ababa ahead of the talks, and stressed that Khartoum did not want a war with the South.

Both sides accuse the other of starting the fighting, the worst violence since South Sudan declared independence from Khartoum last July after decades of civil war.

South Sudan said northern bombers and troops had struck first on Monday, moving into Unity State before Southern troops fought back and took the Heglig oil field, parts of which are claimed by both countries. Sudan later recaptured the field.

U.S. Secretary of State Hillary Clinton accused Khartoum of bearing most of the responsibility for the renewed hostilities.

The AU, UN Security Council and European Union have all called for an end to the fighting. Officials in South Sudan's Unity state said the border was calm Thursday, although northern warplanes were reported to be still flying over the state.