Anna Nicole Smith's file was among those accessed, AP reports
A US state department review has found that the passport files of several high-profile Americans have been accessed, the Associated Press reports.
It comes a week after revelations that workers improperly viewed the files of the three presidential candidates.
Other Americans whose files had been viewed since January 2007 included late Playboy model Anna Nicole Smith, AP reports, citing unnamed officials.
AP says the review is not complete and the number of cases is not yet clear.
State department officials told AP the review involved several hundred US citizens whose passport files are flagged for extra protection because of their prominence.
These people include politicians, entertainers and athletes. Accessing their files triggers an automatic record that it has been viewed.
State department investigation
It is not yet clear whether the new cases involved state department workers gaining unauthorised access to the files, or whether they were legitimate.
US passport files contain details of age and place and birth. They also include an applicant's social security number, which can be used to gain personal information such as credit records.
The state department review is going on at the same time as an internal investigation, launched last week, into breaches of the passport files of the three main presidential candidates.
Ms Rice apologised to the three candidates for the earlier breaches
Secretary of State Condoleezza Rice apologised to all three candidates, when it emerged that state department contractors had improperly viewed the files of Republican John McCain and Democrat Barack Obama, while a trainee had accessed Hillary Clinton's file.
The state department has said it believes the breaches were the result of "imprudent curiosity".
Officials told AP that the review of Anna Nicole Smith's passport file appears to have come from a legitimate request from the US embassy in the Bahamas for information needed to complete her death certificate.
The former model and TV celebrity died in February 2007 from an accidental overdose in Florida. She was buried in the Bahamas, where she had moved in 2006.