It will take several years to solve the problems at one of the Home Office bodies responsible for the failure to consider deporting 1,019 foreign criminals, a top civil servant has admitted.

Lin Homer, head of the Immigration and Nationality Directorate (IND), also said several hundred of the criminals involved have been allowed to stay in the country.

Giving evidence to the Commons home affairs committee, she said: "I suspect it will continue to take us a number of years to become as strong in performance management as I would hope and expect us to be."

She said part of the problem was caused by a lack of managers at the IND to supervise junior staff.

The revelations in April led to the removal of former home secretary Charles Clarke and the suspension of a senior civil servant, and Homer told the committee she felt she had let Clarke down.

Current home secretary John Reid recently described the department as "not fit for purpose", and has admitted to the same committee that figures supplied by civil servants have proved unreliable.

Committee chairman John Denham, a former Home Office minister, said it was "extraordinary" that Homer could not provide "very basic pieces of information" about the number of bail applications being made by those offenders who had been traced, and the department's success in defeating such applications.

Homer said a detailed review of figures was under way and the home secretary would inform parliament when it was complete.

She said in "several hundred" cases reviewed by the IND, it had decided not to deport the criminals.

She revealed eight serious offenders are still on the run from the authorities, and when asked if any more serious offenders had made bail applications, she said she thought one had applied, and she thought bail had been granted.

Shadow home secretary David Davis said Homer's evidence demonstrated the Home Office "still has not got control of this scandal", while Liberal Democrat home affairs spokesman said the "desperate mess" had been caused by a government "obsessed with headlines and legislation".