South Sudan’s vice president flew to Khartoum on Saturday on a mission to “ease tensions” over Abyei, one week after northern troops overran the contested border region, a southern official said. “A high-level delegation led by the vice president, Riek Machar, has gone to Khartoum,” said Mangar Amerdid, a spokesman in the office of the southern president. “It is aimed as an effort to normalise and ease tensions, and to improve the situation in Abyei,” he added, but could not confirm who the southern team would meet in the north.