The United Nations should impose sanctions on Sudan for failing to obey a Security Council resolution calling for an end to hostilities and renewed negotiations with South Sudan over oil and border disputes, South Sudan’s negotiator said on Friday.Pagan Amum told Reuters Khartoum had not complied with the May 2 resolution giving neighbours Sudan and South Sudan, under threat of sanctions, two weeks to resume talks over their differences, which boiled over into border clashes last month.He said while South Sudan, which became the world’s newest independent nation last year, had signalled its readiness to restart talks immediately, its neighbour had carried out air attacks after May 2 and had not moved to resume negotiations."They have violated the timeline,” Amum, Secretary-General of South Sudan’s ruling Sudan People’s Liberation Movement (SPLM), said in an interview in the South Sudanese capital Juba.He urged the U.N. Security Council to "impose sanctions now and take measures against Khartoum”.A spokesman for Sudan’s Foreign Ministry said Amum’s remarks were "unfortunate” and accused the south of violating the Security Council resolution by continuing its "aggression” in Sudan’s territory.While insisting the South wanted to live in peace with Sudan, Amum criticised both the United Nations and the African Union for failing to deal firmly with Sudan, which he said routinely defied the international community."If the U.N. fails to take action, they will be judged by humanity and the people of South Sudan will lose trust and confidence in them,” the South Sudanese negotiator said."We are going to ask them, ‘What are you going to do?’”He said he had written to former South African President Thabo Mbeki, who is in Khartoum as head of the AU panel tasked with resolving the north-south disputes, asking when the negotiations with Khartoum would restart but had not so far received a response.El-Obeid Morawah, Sudan’s Foreign Ministry spokesman, said: "The Security Council and the AU have their own monitoring mechanisms and it is they who will say which side violates the decisions. I think it is better for them (South Sudan) and for us to put the negotiations first.”On Thursday, the U.N. Security Council demanded that Sudan immediately withdraw troops from the disputed Abyei border region but Khartoum pledged only to do so after a joint military observer body for the area was created.Amum said South Sudan had withdrawn its police forces from Abyei in compliance with the U.N. demands and said Khartoum’s failure to pull out its military was a violation that should be punished by the Security Council.