The findings of the official investigation into the relaxation of border checks last year is to be published by Home Secretary Theresa May.
The official investigation into the relaxation of border checks last year found confusion, poor record-keeping and ambiguous instructions were rife in the UKBA and border force staff were acting without ministerial approval.
John Vine, the independent chief inspector of the UKBA, found about 500,000 Eurostar passengers boarded trains in France and arrived in the UK without being checked against the warnings index of suspected terrorists and those with adverse immigration histories.
He also found border security checks had been suspended regularly and applied inconsistently since at least 2007.
One scheme at London's Heathrow Airport let students from supposedly low-risk countries in even when they did not have the necessary entry clearance in a move which was both "potentially discriminatory and unlawful".
The Home Secretary said: "The Vine report reveals a border force that suspended important checks without permission; that spent millions on new technologies but chose not to use them; that was led by managers who did not communicate with their staff; and that sent reports to ministers that were inaccurate, unbalanced and excluded key information."
The border force "needs a whole new management culture", Mrs May said. "There is no getting away from the fact that UKBA, of which the border force is part, has been a troubled organisation since it was founded in 2008. From foreign national prisoners to the asylum backlog to the removal of illegal immigrants, it has reacted to a series of problems instead of positively managing its responsibilities."
From next month, "the UK border force will be split from UKBA and will become a separate operational command, with its own ethos of law enforcement, led by its own director general, and accountable directly to ministers".
Mr Clark welcomed "the recognition of the complexity of the business" in the report and said he hoped its recommendations "will serve to remove some of the barriers to success that currently exist".
"The Home Secretary's statement gives only a partial picture of the report's contents and does not acknowledge its full findings, including the criticisms of ministers," he said. The FDA, the union representing Mr Clark, added that it showed the former head of the border force was no rogue official acting alone within the agency.