US Democratic candidate Hillary Clinton has said her passport file was improperly accessed by officials at the state department.
The passport files of the three leading US presidential candidates have been improperly accessed, the state department has said.
US Secretary of State Condoleezza Rice contacted Mrs Clinton about the breach, Mrs Clinton's senate office said.
A state department employee looked at the files of both Republican candidate John McCain and Democratic front-runner Barack Obama, the department said.
It comes Ms Rice apologised to Mrs Clinton's Democratic presidential rival Barack Obama over a breach of his passport records.
State department spokesman Sean McCormack said a trainee also accessed Hillary Clinton's file last year.
Two state department contractors have been fired and a third disciplined.
Two state department contractors have been fired and a third disciplined.
"In the case of Senator McCain, we detected earlier this year... one of the same people who accessed Senator Obama's passport file also accessed Senator McCain's passport file," Mr McCormack said.
That staff member has been reprimanded but not fired, he said.
Earlier on Friday, Ms Rice said she had apologised to Mr Obama about the breach of security regarding his passport file.
She said a full investigation was under way.
A spokesman for Mr Obama suggested that the government could be using private information for "political purposes".
A spokesman for Mr Obama suggested that the government could be using private information for "political purposes".
The BBC's North America editor, Justin Webb, says it is an extraordinary lapse in security which allowed temporary state department employees access to personal information on a man who is guarded by the secret service day and night.
The spokesman, Bill Burton, denounced "an outrageous breach of security and privacy", and called for a full investigation.
'Very disturbed'
Mr McCain said any breaches of passport privacy called for an apology and a full investigation. He said "corrective action should be taken".
The state department tracks those who access its passport database.
Breaches occurred on three separate dates - 9 January, 21 February and 14 March.
The Obama campaign raised the possibility of political motivationMs Rice said she had telephoned Mr Obama, a Democratic candidate, to apologise over the lapses in security.
"I told him that I was sorry and I told him that I myself would be very disturbed if I learned that somebody had looked into my passport file," she told reporters.
She said the state department's inspector general was investigating the case with the Department of Justice.
The unauthorised viewings were noticed at a lower level, Ms Rice said, but senior management was not informed.
The incidents were brought to the attention of higher officials by a reporter.
Mr McCormack said it was not clear what the employees may have seen or what they were looking for.
Bill Burton, a spokesman for Mr Obama's campaign, denounced "an outrageous breach of security and privacy", and called for a full investigation.
"We demand to know who looked at Senator Obama's passport file, for what purpose, and why it took so long for them to reveal this security breach," he said.
