North Carolina has halted the research of reading specialist Mary Willingham until she receives approval from a review board and is investigating statements she made questioning the literacy level of Tar Heels athletes.

In an open letter emailed to university students, faculty and employees Thursday, chancellor Carol Folt said she takes Willingham's allegations "very seriously." But the chancellor said the school has been "unable to reconcile these claims with either our own facts or with the data currently being cited as the source for the claims."

"Nevertheless, we are investigating all the claims being made and, if they are found to have merit, I will take all appropriate actions," Folt said. "We also will do our best to correct assertions we believe are not based in fact."

In a CNN story last week, Willingham said her research of 183 football or basketball players at UNC from 2004 to 2012 found 60 percent reading at fourth- to eighth-grade levels and roughly 10 percent below a third-grade level. She said she worked with one men's basketball player early in her 10-year tenure who couldn't read or write.

Willingham hasn't returned calls from The Associated Press and didn't respond to emails Thursday.

UNC coach Roy Williams and the school have refuted the report.

The school said in a statement Thursday evening that it has notified Willingham she can't continue to use data with information that could identify the subjects until she applies to the university's review board that governs human research. Researchers don't require board approval for research if it doesn't include identifiable information on the subjects, the school pointed out in the statement.

Willingham's research work dates back to 2008. The UNC statement also said Willingham had provided the data that led to her findings to provost James W. Dean Jr. earlier this week.

In Folt's letter, also posted on the university's website, she said two of 321 athletes admitted in 2012 and 2013 fell below test thresholds used in the CNN report -- a 400 on the SAT critical reading or writing test, or a 16 on the ACT -- about reading levels for first-year students nationally. Folt said both are currently in good academic standing.

The school also released an analysis from its admissions office saying that more than 97 percent of 1,377 first-year student-athletes admitted through special-talent policies between 2004 and 2012 met the standard in the CNN report. Thirty-four of the 39 who didn't meet the standard have graduated, are enrolled in good standing or are academically eligible to return.

Folt, a former interim president at Dartmouth, is in her first academic year after replacing Holden Thorp. Thorp left last year amid the fallout of an NCAA investigation into the football program in 2010 that eventually led to the discovery of fraud in an academic department with classes featuring significant athlete enrollments. The irregularities ranged from no-show classes to unauthorized grade changes stretching back to 1997, and has led to the recent indictment of the retired department chairman who was paid to teach a lecture course that didn't meet and was instead treated as an independent study requiring a research paper.

In an interview with The News and Observer of Raleigh on Wednesday, former football player Michael McAdoo -- who was ruled permanently ineligible for academic misconduct during the NCAA probe -- said school academic advisers guided him to four of the department's no-show classes in what he called "a scam."

In all, there have been seven internal and external reviews or investigations since 2011 resulting in more than 70 recommendations to improve policies and procedures.

"I still have many questions, and I am seeking to understand the complete picture of what additional work we need to do in this area," Folt said. "We have learned many lessons in the past few years, and I am actively building on those lessons to continue to improve our community."