UNITED NATIONS, May 12 (AP/UNB) — The United Nations said Friday that South Sudan has pulled its police force out of the disputed Abyei region on the border with Sudan.

The withdrawal Thursday follows a U.N. Security Council resolution last week threatening nonmilitary sanctions against both countries if they don't stop attacking each other and return to negotiations.

South Sudan won independence from Sudan last year as part of a 2005 peace treaty that ended decades of war that killed 2 million people. But the neighboring nations have been drawing closer to full-scale war in recent weeks over unresolved issues of oil revenues and their disputed border.

About 700 South Sudanese police officers had returned to South Sudan on Thursday, and the U.N. mission was verifying none were left in oil-rich Abyei, according to a statement by U.N. spokesman Martin Nesirky.

U.S. Ambassador Susan Rice praised the South's move as "an important step toward ending the border dispute with Sudan," and urged Sudan to also withdraw its troops from Abyei.