David Bell, the permanent secretary at the Department for Children, Schools and Families, told the Commons education select committee that when he took up the post at the then DfES in December 2005, there were 180 officials waiting in an "unallocated" pool.
He said: "If someone was working on a project that came to an end, they then sat in a pool without being allocated to a new substantive job or the department deciding that they should leave," and there had been too many people in that position.
Barry Sheerman, the committee chair, said: "I find this astounding. In any organisation I have ever known people don't go from doing a job to doing nothing."
Mr Bell said that unallocated officials "might be" given a series of temporary assignments. "We have sorted that and it is dealt with; it is history," he said. But officials who had completed projects still had a "three month window" to look at alternatives before they were reallocated or moved on.
Mr Bell suggested that the non-allocated pool practice was used in other Government departments.