Washington: State Department workers viewed passport applications containing personal information about high-profile Americans, including the late Playboy playmate Anna Nicole Smith, at least 20 times since January 2007, it has now emerged.

That total is far more than disclosed last week with news that presidential candidates Hillary Clinton, John McCain and Barack Obama had been victims of improper snooping.

An internal department review found the additional instances of department employees or contractors looking at computerised passport files of politicians and celebrities, according to preliminary results. It has not been determined whether the new cases also involved improper looking, officials familiar with the review said on Wednesday. Smith's case, however, seems legitimate, the officials said. The review is not complete and the number of cases was not yet clear.

The officials spoke on condition of anonymity because the review is going on at the same time as the department's own watchdog investigates passport record security related to the breaches involving the White House candidates.

Smith died in the Bahamas in February 2007. The review of her passport file appears to have come after a legitimate request from the US Embassy in the Bahamas for information needed to complete her death certificate, the officials said.

Flagged files

Supervisors recorded each instance a file was viewed because the applications in question belonged to members of a select group of several hundred citizens whose passport files were "flagged" for extra protection due to their visibility, the officials said. Among these people are government leaders, movie stars and athletes, the officials said.

The list maintained by the Bureau of Consular Affairs has included as many as 500 names at any one time, they said.

The list is kept secret partly to deter workers from making unauthorised inquiries into high-profile records.

The investigation begun by the department's inspector general after last week's disclosure covers some of the same ground as the internal review but also will examine whether the searches of the candidates' records were politically motivated. Thus far, officials say they believe that snooping resulted from "imprudent curiosity." Two contractors were fired and a third disciplined for breaching Obama's records three times and McCain's records once. A department employee who looked at Clinton's file as part of a training exercise was reprimanded.

Accessing any of the flagged files triggers an automatic notification that the record has been viewed. That allows supervisors to check whether it was done for a legitimate reason, such as an official request for verification of information contained in a passport.

The review being conducted by Patrick Kennedy, undersecretary of state for management, is expected to result in increased security measures for the passport files of flagged individuals, the officials said.