The confidential passport files for all three presidential candidates — Barack Obama, Hillary Clinton and John McCain — have been improperly accessed by US State Department workers, it emerged last night.

The announcement came hours after it was revealed that two State Department workers had been dismissed and a third disciplined, for improperly accessing Mr Obama’s passport file on three occasions this year. It was also revealed that no senior officials were notified of the breach.

The revelations raised questions over whether any of the breaches were politically motivated, and why it took so long for the unauthorised snooping to emerge. The first occasion when Mr Obama’s file was accessed took place on January 9, 71 days before senior officials at the State Department were alerted to the multiple infringements.

Hours after dealing with questions about the accessing of Mr Obama’s passport files, Condoleezza Rice, the US Secretary of State, announced that Mrs Clinton’s files were also accessed improperly once last year.

Minutes later, the State Department admitted that John McCain’s files were breached on March 14 — by the same person, and on the same day that Mr Obama’s was looked at for a third time.

Sean McCormack, Dr Rice’s spokesman, said that the worker who had accessed the files of Mr Obama and Mr McCain had so far only been disciplined and had not been dismissed.

He said that the breach of Mrs Clinton’s file occurred during a training session last summer. Trainees are encouraged to enter names of their families to show how the system works, Mr McCormack said.

“This person entered Senator Clinton’s name. It was immediately recognised, [the trainee] was admonished, it didn’t happen again,” he said. Mrs Clinton issued a statement saying that she had been told by Dr Rice that her file had been breached in 2007.

In one of the more bizarre days of the presidential campaign, Dr Rice first told reporters that she had telephoned Mr Obama to apologise for the breaches, which because of their frequency and timing, appear potentially more disturbing than the others. “I told him I was sorry, and I told him that I myself would be very disturbed,” she said.

Dr Rice expressed concern that the breaches were not reported right away. She said that her office became aware of them only when a reporter made an inquiry on Thursday afternoon. She said that the incidents “should have been made known to senior management. It was not, to my knowledge, and we also want to take every step we can to make sure this kind of thing doesn’t happen again”.

Mr Obama’s files were breached on January 9, February 21 and March 14 this year. “When you have not just one but a series of attempts to tap into people’s personal records — that’s a problem, not just for me but how our government is functioning,” Mr Obama said yesterday.

Bill Burton, a spokesman for Mr Obama, said: “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 them so long to reveal this security breach.” Mr McCormack said on Thursday night that the breaches appeared to be no more than “imprudent curiosity”.

Patrick Kennedy, the State Department’s top management officer, said that the department’s Inspector General had begun a full investigation.

Mr Kennedy said the employees were contract workers. He added that 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.

“I fully acknowledge this information should have been passed up the line,” Mr Kennedy said. “It was dealt with at the office level.”

In 1992, a Republican political appointee at the State Department was demoted after searching through the passport records of Bill Clinton when he was running for president. The official was searching for information to back up what turned out to be a false rumour that Mr Clinton had at one time renounced his US citizenship to avoid the Vietnam draft.

Joseph DeGenova, a lawyer who investigated that incident in 1992, said of the Obama breaches: “It’s really remarkable that something like this could have gone unreported. What’s disturbing about it is there are three separate breaches. It strains the imagination that somehow they were not linked.”

How state scandals came to light

— Last year, the US State Department revealed that an international ring of hackers stole data from its network after an employee in Asia opened an e-mail that allowed them to break into the Government’s computer system

— In 2000 undercover investigators for the General Accounting Office posed as law enforcement officers and gained access to 19 federal buildings and to two of the US’s busiest airports

— In 1999 a Russian listening device was found inside the State Department conference room, where secret discussions are held In 1992 a Republican political appointee at the State Department was demoted over a search of Bill Clinton’s passport records. At the time he was challenging President George H.W. Bush

— In 1977 Richard Nixon refused to relinquish to a Senate committee tapes of conversations held in the President’s office. Public outcry forced him to surrender them, exposing clear evidence of his involvement in what became known as the Watergate scandal. Nixon resigned on August 8, 1974 and was later pardoned by President Ford

Source: Times archives

Times Recommends

• No cause for celebration in crushed Sarajevo
• Jazz funeral for the final victims of Katrina
• French fined for 'insulting' civil servants