Delays in implementing a crisis-hit border security system could be undermining Britain's security, MPs have warned in a report.
The Home Office has been told to "get its house in order now" after a long-awaited system to create E-borders to better screen people coming into the country is set to cost £1 billion and be at least eight years late.
Only 86% of those coming to Britain have their data checked ahead of travel, despite a pledge to carry this out on 95% of travellers by December 2010.
Meg Hillier, chairwoman of the Public Accounts Committee which produced the report, told the Press Association this extra security check is designed to root out serious criminals and terrorists before they arrive in Britain.
She said: "If you collect information before people arrive the more chance you have to stop them entering the country in the first place.
"That's the prize - to stop the people who mean to do this country harm, terrorists or criminals, to stop them coming into the country in the first place.
"That's the whole point - E-borders was to track people and catch people early and to focus on the people who are most likely to be dangerous."
The controversial scheme was devised in 2003 to enhance checks on those entering the country by air, rail and sea by gathering and processing data on passengers before they reach the border.
Since then the Home Office has racked up hundreds of millions of pounds in costs, including a £150m settlement following a legal dispute after the original contract was cancelled in 2010.
The new system is now expected to come into force at the earliest by 2019 - eight years later than planned and could face further delays, the committee warns.
It said warnings about the troubled project were brushed aside and continual changes in senior management have "hindered" its completion.
And it said the Home Office "does not have a clear picture of the management information it has or needs to manage the UK border which is hindering its operations".
The report states: "Since 2010 the Major Projects Authority has issued seven warnings about these programmes.
"Former and current officials were worryingly dismissive that these warnings and concerns suggested fundamental problems and said that all recommendations had been implemented.
"It is difficult to understand where this confidence had come from, given the lengthy delays and continual warnings of ongoing management issues, which gives us cause for concern about the future prospects for this programme which is vital to national security."
Mrs Hillier said the report revealed "a history of poor management and a worrying complacency about its impact on taxpayers".
She added: "It is accepted that successful completion of this project is essential to the security of our international borders. Yet the original target date has long passed and we are still at least three years away from delivery.
"The stop, start approach has cost the taxpayer dear."
She added: "If the Home Office is to complete this project before the decade is out then it must get its house in order now - starting by setting out exactly what it expects to achieve this year, and who will be held to account for it."