WASHINGTON (Reuters) - President Barack Obama on Wednesday urged leaders of north and south Sudan to build on their agreement to ease tension in the disputed region of Abyei by undertaking an immediate ceasefire in Southern Kordofan.
"The situation in Southern Kordofan is dire, with deeply disturbing reports of attacks based on ethnicity," Obama said in a statement.
The oil-rich region is in the north but is also home to thousands of south-aligned fighters, which the north sent forces to confront earlier this month.
Human rights activists say the north has targeted the Nuba population. Khartoum denies the accusation.
South Sudan is set to secede from the north on July 9, but unresolved conflicts in a number of parts of the country, split for decades over religion, ethnicity and natural resources, threaten to mar the process.
The north poured troops and tanks into Abyei on May 21, sparking a panicked exodus of more than 100,000 people who fled fighting in a region prized for its oil and commercial value.
The two sides, which have been at war for many of the last 56 years, agreed on Monday to pull out troops from Abyei and bring in Ethiopian peacekeepers, but tensions remain high.
"I commend the parties for taking this step forward toward peace, and I urge them now to build on that progress and agree to an immediate cease fire in Southern Kordofan," said Obama.
His administration has offered Khartoum improved relations with Washington in return for not fanning violence, but Obama made plain that was conditional.
"With a ceasefire in Southern Kordofan, alongside the agreement to deploy peacekeepers to Abyei, we can get the peace process back on track," he said.
"But without these actions, the roadmap for better relations with the Government of Sudan cannot be carried forward, which will only deepen Sudan's isolation in the international community."
(Reporting by Alister Bull; Editing by Jackie Frank)