WASHINGTON (AP) _ The State Department says it is trying to determine whether three contract workers had a political motive for looking at Democratic presidential candidate Barack Obama's passport file.

Two of the employees were fired for the security breach and the third was disciplined but is still working, the department said Thursday night. It would not release the names of those who were fired and disciplined or the names of the two companies for which they worked. The department's inspector general is investigating.

State Department spokesman Sean McCormack said that for now it appears that nothing other than "imprudent curiosity" was involved in three separate breaches of the Illinois senator's personal information, "but we are taking steps to reassure ourselves that that is, in fact, the case."

It is not clear whether the employees saw anything other than the basic personal data such as name, citizenship, age and place of birth that is required when a person fills out a passport application.

Bill Burton, a spokesman for Obama's presidential campaign, called for a complete investigation.

"This is an outrageous breach of security and privacy, even from an administration that has shown little regard for either over the last eight years," Burton said. "Our government's duty is to protect the private information of the American people, not use it for political purposes."

"This is a serious matter that merits a complete investigation, and 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.

The breaches occurred on Jan. 9, Feb. 21 and March 14 and were detected by internal State Department computer checks, McCormack said. The department's top management officer, Undersecretary Patrick Kennedy, said certain records, including those of high-profile people, are "flagged" with a computer tag that tips off supervisors when someone tries to view the records without a proper reason.

The firings and unspecified discipline of the third employee already had occurred when senior State Department officials learned of the breaches. Kennedy called that a failing.

"I will fully acknowledge this information should have been passed up the line," Kennedy told reporters in a conference call Thursday night. "It was dealt with at the office level."

In answer to a question, Kennedy said the department doesn't look into political affiliation in doing background checks on passport workers. "Now that this has arisen, this becomes a germane question, and that will be something for the appropriate investigation to look into," he said.

The department informed Obama's Senate office of the breach on Thursday. Kennedy said that at the office's request, he will provide a personal briefing for the senator's staff on Friday. No one from the State Department spoke to Obama personally on Thursday, the officials said.

Obama was born in Hawaii and lived in Indonesia for several years as a child before returning to the United States. As a member of the Senate Foreign Relations Committee, he has traveled to the Middle East; the former Soviet states with Sen. Richard Lugar, R-Ind.; and Africa, where in 2006 he and his wife, Michelle, publicly took HIV tests in Kenya to encourage people there to do the same.

Obama's father was born in Kenya, and the senator still has relatives there.

The disclosure of inappropriate passport inquiries recalled an incident in 1992, when a Republican political appointee at the State Department was demoted over a search of presidential candidate Bill Clinton's passport records. At the time he was challenging President George H.W. Bush.

The State Department's inspector general said the official had helped arrange the search in an attempt to find politically damaging information about Clinton, who had been rumored to have considered renouncing his citizenship to avoid the Vietnam War draft.

The State Department said the official, Steven Berry, had shown "serious lapses in judgment."

After a three-year, $2.2 million probe, a federal independent counsel exonerated officials in the incident, saying that while some of the actions investigated were "stupid, dumb and partisan," they were not criminal. The independent counsel also said that Berry and others who were disciplined for their involvement were treated unfairly.

Doug Hattaway, a spokesman for Sen. Hillary Rodham Clinton, the former first lady who is challenging Obama for the Democratic presidential nomination, said of the current breach: "It's outrageous and the Bush administration has to get to the bottom of it."

Kennedy and McCormack said it was too soon to say whether a crime was committed. The searches may violate the federal Privacy Act, and Kennedy said he is consulting State Department lawyers.

The State Department inspector general's power is limited because two of the employees are no longer working for the department. McCormack said it was premature to consider whether the FBI or Justice Department should be involved.

McCormack said Secretary of State Condoleezza Rice was informed of the breaches on Thursday.