BILOXI, Miss. (AP) — Federal housing authorities are auditing the use of more than $650 million in grants designated for an ambitious plan for sewage and water systems across south Mississippi in the wake of Hurricane Katrina, The Associated Press has learned.

The money was divided among five south Mississippi counties, with the most, more than $230 million, set aside for the largest, Harrison County. The entire plan is being audited by the Office of Inspector General for the U.S. Department of Housing and Urban Development, said Robbie Wilbur, spokesman for the Mississippi Department of Environmental Quality. Wilbur's agency hired engineering firms to draft the Gulf Region Water and Wastewater Plan after Hurricane Katrina struck in August 2005.

HUD officials would not comment on whether an audit is being done.