An internal investigation by the U.S. State Department has found that government employees repeatedly accessed the passport files of more than 100 high-profile Americans.

The investigation was prompted by revelations in March that department employees had looked into the passport files of Democratic Senators Hillary Clinton and Barack Obama, and Republican Senator John McCain - the three remaining major U.S. presidential candidates at the time.

In a report issued Thursday, the department's inspector general says investigators complied a list of 150 famous U.S. citizens.  They found that the files of 127 people, or 85 percent of the list, had been viewed, some of them multiple times.

The report does not say whether the files were accessed for legitimate reasons, but notes the number of viewings appears excessive.

The inspector general made 22 recommendations for improving security, including random audits of files and decreasing the number of people authorized to view the records.

Some information for this report was provided by AP.