RALEIGH, N.C. (AP) — North Carolina officials say they will retest seven residential wells near Duke Energy coal ash dumps for contamination after homeowners were prematurely assured their water is safe to drink.

The homeowners were sent letters by the North Carolina Department of Health and Human Services in recent weeks saying water from their wells met all state health screening levels. Agency spokeswoman Alexandra Lefebvre now says the tests performed by the commercial laboratory that processed the samples weren't sensitive enough to measure potentially harmful chemicals down to the state screening levels.

The decision to retest the wells was made late last month after The Associated Press questioned the validity of the results.

"Well sampling and resampling is an ongoing process and our goal remains to help residents make the most health protective choices for their families," Lefebvre said Tuesday.