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 has said.

Pagan Amum yesterday said 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," Mr Amum, secretary-general of South Sudan's ruling Sudan People's Liberation Movement (SPLM), said in the South Sudanese capital Juba.

He urged the UN to "impose sanctions now and take measures against Khartoum".

A spokesman for Sudan's Foreign Ministry said Mr 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, Mr Amum criticised both the UN and the African Union (AU) for failing to deal firmly with Sudan, which he said routinely defied the international community.

"If the UN fails to take action, they will be judged by humanity and the people of South Sudan will lose trust and confidence in them," he 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 UN 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.

Mr Amum said South Sudan had withdrawn its police forces from Abyei in compliance with the UN demands and said Khartoum's failure to pull out its military should be punished.

The South accuses Khartoum of launching bombing raids on its territory after May 2. UN peacekeepers have verified damage and casualties from at least one raid and the UN's top human rights official said last week she was outraged by "indiscriminate" aerial attacks by Sudan.

Mr Amum added: "The UN sees it as normal for [Sudanese President Omar Hassan al] Bashir to bomb and kill the people of South Sudan. The conscience of the international community is not pricked ... they are used to it, it has become normal."

The two Sudans, which fought a civil war for more than two decades before a 2005 peace deal that eventually led to South Sudan's independence, sit on significant oil reserves.

A dispute over the fees South Sudan should pay to Sudan to export its crude through the north prompted Juba to shut off its oil production earlier this year.