JUBA May 6 U.N. Secretary General Ban Ki-moon flew into South Sudan on Tuesday to urge government troops and rebels to end more than four months of fighting - the second peace mission there by a major global figure in less than a week.
Ban was expected to meet South Sudanese President Salva Kiir, part of a mounting international push to stop the increasingly ethnic violence that Washington and regional powers fear could descend into genocide.
U.S and other diplomatic sources told Reuters on Monday Washington would back up the diplomacy with sanctions on figures from both sides of the conflict in coming days.
Showing the message had hit home, a South Sudanese official said there was no need to sanctions on the government side, as the president had already responded to international pressure and agreed to hold talks with the main rebel leader.
"(The government is) doing precisely what has been asked," Ministry of Foreign Affairs spokesman Mawien Makol Arik told Reuters.
Thousands of civilians have been killed and more than a million have fled since fighting started in mid December between troops loyal to Kiir and fighters backing his sacked deputy Riek Machar.
Fighting quickly spread, often along ethnic lines, pitting Kiir's Dinka people against Machar's Nuer.
Government and rebel negotiators in Ethiopia agreed on Monday to consider a "month of tranquillity", but as they did, rebel fighters and the army battled for control of a northern oil town.
Aid workers in Bentiu reported no fighting on Tuesday. Both sides claimed control of the town, capital of oil producing Unity state and scene of an ethnic massacre last month that fuelled fears of a genocide.
Kiir agreed to hold face-to-face talks with Machar after meeting U.S. Secretary of State John Kerry in the South Sudanese capital Juba on Friday.
The top U.S. diplomat failed to win a similar commitment in a phone conversation with Machar and later threatened to hit the rebel leader with sanctions if he did not take part. (Reporting by Andrew Green; Writing by Richard Lough; Editing by George Obulutsa and Andrew Heavens)