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An independent report has found that successive governments have spent £830 million on a border control system which is four years overdue - and it won't be finished until 2019.
The e-borders project, designed to improve security by collecting and storing advance information on passengers and crew from all ports and airports, will likely require a further £275m by March 2019.
Meanwhile, £89 million has been invested on improvements to the old systems which e-borders were supposed to replace.
A National Audit Office report has criticised the time and expense taken on the project, begun in 2007.
The government set a target of April 2011, but at the time of writing the old system is still being used, with data only being received in advance for 86 per cent of those travelling to the UK.
The National Audit Office says checks remain "highly manual and inefficient", and IT systems currently used are outdated.
The report said a database called the 'Warning Index' was still being used eight years after it should have been retired, and suffers an average of two "high priority incidents a week".
The system was described as "still far from good", as incidents include performance too slow to function, or inaccessibility at sometimes over 30 per cent of control points at ports or airports.
The Home Office said that contingency plans were in place for such incidents.
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