Washington United States President Barack Obama Sunday greeted the “historic” start of voting in the Southern Sudan independence referendum but called for an end to violence in the disputed border region of Abyei.

He also sent a message apparently aimed at the government in Khartoum that “the world will be watching in the coming days.” “The United States will remain fully committed to helping the parties solve critical post—referendum issues regardless of the outcome of the vote,” Mr. Obama said in a statement.

The referendum saw Southern Sudanese going to the polls on Sunday in a vote that is widely expected to see them decide to split from the north.

The week—long vote is the centerpiece of a 2005 peace deal that ended decades of civil war between the mainly Muslim north and the Christian and Animist south — a conflict that claimed the lives of more than 2 million southerners and displaced 4 million more.

Fighting in the disputed border region of Abyei over the weekend led to as many as nine deaths, an official said. The fighting was reportedly between members of the Ngok Dinka and Misseriya tribes.

The oil—producing area was originally scheduled to hold a referendum on Sunday to decide whether to remain united with the north or join an independent south. That vote has been postponed.

Neither side can agree on whether the Misseriya, a nomadic tribe that travels through Abyei each year, should have the right to vote.

Sudanese President Omar al—Bashirhas said he believes Abyei has the potential to reignite civil war — a sentiment echoed by many observers.

Mr. Obama noted that a successful vote would be “cause for celebration” but warned that “an enormous amount of work remains to ensure the people of Sudan can live with security and dignity.” “The international community is united and determined to ensure that all parties in Sudan live up to their obligations,” Mr. Obama said.

He called for restraint from “inflammatory rhetoric and provocative actions” that could interfere with the people of Southern Sudan “expressing their will.”

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