By Hereward Holland
JUBA (Reuters) - The U.N.'s top human rights official on Friday said she was outraged by Sudan's "indiscriminate" aerial bombing of South Sudan and warned that attacks that hurt civilians could be considered international crimes.
Navi Pillay, the U.N. High Commissioner for Human Rights, condemned the attacks by Khartoum during a visit this week to newly-independent South Sudan, whose government she also urged to adhere to international human rights treaties.
Last month, Sudan and South Sudan fought skirmishes on their disputed border, prompting a May 2 warning from the U.N. Security Council to both sides that if they did not settle their differences peacefully they could face sanctions.
On Wednesday, South Sudan accused Sudan of bombing and shelling seven areas on the southern side of the border, calling the acts a violation of a U.N.-backed ceasefire that should have begun on Saturday.
"Deliberate or reckless attacks on civilian areas can, depending on the circumstances, amount to an international crime," Pillay told reporters at the U.N. mission at the South Sudanese capital of Juba.
Pillay said she had previously condemned what she called "indiscriminate" aerial bombings by Sudan's armed forces of South Sudanese territory.
"I am saddened and outraged to learn that such attacks which place civilians at great risk - and have already killed and injured some and caused many thousands of others to flee - have been taking place again in recent days," Pillay said.
Limited access to the border makes it difficult to verify contradictory statements from Juba and Khartoum, and Sudanese military spokesmen routinely deny South Sudan's accusations.
The two old civil war foes have been at loggerheads over unresolved issues regarding oil exports, border demarcation, citizenship and financial arrangements since South Sudan broke away to become the world's newest nation last July.
U.N. peacekeepers visited two South Sudanese sites allegedly bombed by warplanes from Sudan a week ago and found several craters, according to U.N. officials. They also confirmed a woman and child were injured, the U.N. officials said.
U.S. Secretary of State Hillary Clinton has called on Sudan to stop all cross-border attacks, including what she called "provocative" aerial bombardments.
Despite the continuing alleged bombings, South Sudan's government has said it is ready to restart negotiations at "any time" with its neighbor Sudan to try to resolve their outstanding oil, security and frontier disputes.
But Sudanese President Omar Hassan al-Bashir has said there can be no such talks unless the sides settle security issues. Sudan accuses South Sudan of supporting rebel militia along the disputed border, a charge denied by Juba.
Pillay said that during her talks with South Sudanese President Salva Kiir and other officials in Juba, she urged them to combat impunity among members of the local security forces, some of whom have been accused of torture and beatings during an civilian disarmament campaign in Jonglei state.
"Human rights are not negotiable and cannot be cherry-picked. There are no excuses, not even the youthfulness of the state, for ignoring or violating them," she said.
In a separate development, Sudan said on Friday it would begin transferring more than 12,000 South Sudanese stuck in Kosti port in White Nile State to Khartoum airport on Saturday for them to be flown to South Sudan.
The evacuation is being assisted by the International Organisation for Migration.
Plans for deals to grant Sudan and South Sudan's citizens reciprocal residency and free movement stalled when Khartoum called off a summit in protest at last month's border fighting.
Sudan also halted river traffic down the Nile in March, accusing Juba of using boats to transport weapons to rebels in the north.
Both countries have suspended direct flights between them. Air travelers between Khartoum and Juba have to take a costlier route via Addis Ababa or Nairobi.
About 400,000 South Sudanese have returned home since October 2010, but more than half a million remain in Sudan.
(Additional reporting by Yara Bahoumy in Khartoum; Editing by Pascal Fletcher and Andrew Roche)