(Adds U.S. and South Sudan comment details, background)

By Louis Charbonneau

UNITED NATIONS, March 3 (Reuters) - The U.N. Security Council on Tuesday established a sanctions regime for South Sudan but stopped short of imposing worldwide travel bans and asset freezes on officials in the conflict-torn country or an arms embargo.

The unanimously adopted resolution, drafted by the United States, threatens to blacklist anyone undermining security or interfering with the peace process after Thursday and April 1 deadlines set by the regional East African IGAD bloc.

IGAD has so far been unsuccessful in its attempts to mediate an end to the civil war, in which at least 10,000 people have been killed and 1.5 million internally displaced. The latest round of IGAD-led peace talks are due to end on Thursday.

Conflict has been rife in South Sudan since December 2013 when fighting erupted in the capital Juba between soldiers allied to President Salva Kiir and those loyal to his former deputy, Riek Machar.

The resolution says future U.N. sanctions steps could include both an arms embargo and the blacklisting of individuals. U.S. officials have said they wanted to take an "incremental approach" and gradually increase pressure on the warring factions in the world's youngest country.

U.S. Ambassador Samantha Power said the council was "sending a very clear signal to those who continue to choose war over peace - you will be held to account now as we urge you to compromise to reach an agreement and later when you are considering whether to follow through on its terms."

South Sudan's U.N. Ambassador, Francis Deng, made clear his displeasure with the resolution, telling the 15-nation Security Council that any move to impose sanctions on individuals key to the peace process "could be counterproductive."

Washington first said it was preparing a South Sudan sanctions resolution on Nov. 5. One of the reasons for the delay, council diplomats said, was a dispute over whether to call for an embargo to stop the flow of weapons to both sides in the conflict.

The United States, Russia and China were initially opposed to the idea of an arms embargo, while European and other council members were in favor of it, the diplomats said. Washington, they noted, had feared an arms embargo would favor the rebels and put the government at a disadvantage.

The United States last year imposed unilateral sanctions on two military officers on opposite sides of the violence. (Additional reporting by Michelle Nichols)