Later, the state department said that one of the employees who looked at Obama's file was also found to have viewed McCain's records.
 
Clinton's file was accessed in summer 2007 by a trainee hired to help relieve the backlog of passport applications at the time, said Sean McCormack, a state department spokesman.

"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," McCormack said.
 
It was unclear whether McCain, in France to meet Nicolas Sarkozy, the French president, was aware that his own records had been accessed.
 
"If anyone's privacy is breached, then they deserve an apology and a full
investigation and I believe this will take place,''  he said when asked about the state department's admission over Obama.

'Outrageous' invasion
 
Obama said on Thursday that US Congress should be involved in any investigation into the breach.
 
"When you have not just one but a series of attempts to tap into peoples' personal records, that's a problem not just for me but for how our government functions,'' Obama said.
 
"I expect a full and thorough investigation. It should be done in conjunction with those congressional committees that have oversight so it's not simply an internal matter."

Rice said the Inspector General's office was to investigate the incident.
 
In focus


In-depth coverage of the
US presidential election

She added that the unauthorised looks were discovered at a lower level within the department but that senior management had not been notified.
 
Sean McCormack, a state department spokesman said it appeared that "imprudent curiosity" was the reason for three separate breaches of Obama's personal information.
 
He said the breaches occurred in January, February and March, and were detected by an internal monitoring system.
 
The state department would not release the names of the contractors involved, or the names of the two companies they worked for.
 
'Political purposes'
 
It is not clear what information the employees gained access to. 
 
Personal data such as name, citizenship, age, social security number and place of birth, which is required when a passport application is completed.
 
In another development, Bill Richardson, the governor of New Mexico, endorsed on Friday Obama's campaign, calling him a "once-in-a-lifetime leader" who can restore America's international image.
 
As a Democratic superdelegate, the former presidential hopeful plays a part in the tight race for nominating votes and could bring other superdelegates to Obama's side. He also has been mentioned as a potential running mate for Obama.