By Ulf Laessing
KHARTOUM (Reuters) - The United States on Wednesday urged Sudan and armed opposition groups to end fighting in the Blue Nile border state and warned Khartoum the violence was hurting its chances of repairing relations with Washington.
But shortly after U.S. Special Envoy to Sudan, Princeton Lyman, spoke to reporters in Khartoum, Sudanese state media reported new fighting in Blue Nile where 50,000 have fled clashes, according to the United Nations.
The Sudanese army fought with armed groups near Bau south of the state capital Damazin and inflicted "heavy losses" on them, an army spokesman told state news agency SUNA. Several soldiers had been killed and injured.
Both Sudan's army and the armed groups allied to the opposition SPLM-North party have blamed each other for starting the violence last week.
"The two sides are not still talking to each other. That means the situation remains very dangerous. Fighting is going on," U.S. Special Envoy Lyman said after meeting Sudan's Foreign Minister, Ali Ahmed Karti, and other officials.
Tensions have mounted in Blue Nile and other territories along Sudan's poorly-defined border with South Sudan since the south declared independence in July.
The territories are all still home to tens of thousands of people from ethnic groups that sided with the south during decades of civil war that led up to independence.
Sudan's government has accused the armed groups of trying to launch a revolution in Blue Nile and the nearby border state of Southern Kordofan and officials last week banned the party, saying it was illegal.
The SPLM-N has accused Khartoum of provoking the fighting to crack down on political opposition in the border regions -- home to most of Sudan's known oil reserves.
Lyman urged Sudan not to clamp down on the SPLM-N.
"If there is going to be a discussion and political talks, who are you going to talk to? Of course you are going to talk to the SPLM-North. It's a major political party in Sudan. Closing down offices does not help," Lyman said.
The SPLM-N said security forces has closed several of its offices and detained several members, according to a statement on Wednesday.
Lyman said Washington wanted to move toward repairing ties with Khartoum after years of U.S. sanctions, but the violence was an obstacle.
"This conflict in Southern Kordofan and Blue Nile raises a number of serious problems. One is the charges of human rights violations that have to be investigated and addressed. The humanitarian crisis has to be addressed," he said.
The United States stepped up sanctions against in Sudan in 1997, accusing the government of human rights abuses and supporting terrorism, then tightening the restrictions still further in 2006 over the separate conflict in Sudan's Darfur region.
Sudan's government had hoped some of those sanctions would be lifted after it kept its promise to recognize South Sudan's independence in July.
AID AGENCIES ACCESS DENIED
Lyman called on Sudan and the armed groups to allow aid agencies into the border areas. The United Nations earlier said the government was not letting aid teams visit Blue Nile.
The SPLM-N was the northern wing of South Sudan's ruling Sudan People's Liberation Movement before the south seceded. SPLM-N has since formed a separate opposition party inside Sudan and the south has dismissed accusations from Khartoum it is backing the fighting.
Lyman urged South Sudan to stay out of the conflict in Blue Nile and South Kordofan and try to encourage the SPLM-N to find a peaceful solution with Khartoum.
Lyman also demanded Sudan and South Sudan resume stalled talks how to share oil revenues within a week.
Khartoum lost 75 percent of the country's 500,000 barrels of oil production when the south became independent on July 9. But the new African nation needs the northern pipeline and port to sell the oil, the lifeline of both economies.
So far, both sides shared revenues equally but have failed to agree on a pipeline transit fee the south will have to pay in the future.
South Sudanese voters overwhelmingly chose to declare independence from the north in a January referendum, a vote promised in a 2005 peace deal that ended the north-south civil war fought over oil, religion, ideology and ethnicity.
(Reporting by Ulf Laessing; Additional reporting by Hereward Holland in Juba; Editing by Rosalind Russell)