GENEVA (AP) — A top U.S. diplomat says the United States has "credible information" that South Sudan's government is targeting civilians in Central Equatoria state and preparing for "large-scale" attacks within days and weeks.

U.S. ambassador Keith Harper told a special Human Rights Council session in Geneva that South Sudan's government has mobilized at least 4,000 militia members and "is staging these fighters in Equatoria to begin conducting attacks."

South Sudan ambassador Kuol Alor Kuol Arop didn't directly reject Harper's claims but responded that the country's vice president and other top officials are part of the transitional government. Speaking to The Associated Press afterward, Arop denied a build-up of forces or plans for an offensive.

Violence has driven tens of thousands of people from restive South Sudan into neighboring Uganda in recent months.