Frontline immigration staff are becoming little more than "box-tickers and rules followers" as a result of the Government's passport-checking policy, according to the former head of the UK Border Force.
Brodie Clark said full passport checks introduced by the Home Secretary last autumn are causing lengthy delays at London's major airports and undermining security.
Writing in The Times he described Theresa May's decision to suspend risk-based border controls as a "kneejerk reaction" and said it would be reinstated.
Clarke argued there has been "a crisis in confidence among border staff" since he resigned from his position last November after allowing certain passenger checks to be relaxed without seeking ministerial approval.
He wrote: "The early journey we took into a more risk-based approach to checking passengers arriving in Britain has been shelved.
"Instead, we are back to the laborious and less effective policy of checking every passenger to a similar level, regardless of whether a particular individual is ever likely to pose a threat.
"It means that sticking to the process becomes the measure of success, not results from checking.
"It means that we give committed frontline immigration staff little opportunity to use their well-developed instincts and experience - they become little more than box-tickers and rules followers."
He added: "The pressures of long queues reduces the effectiveness of border staff - put simply it leads to mistakes."
Clark, who was speaking for the first time since receiving compensation after settling a constructive dismissal case against the Home Office, said the full check policy was meaning staff were being moved away from "vital security work" and instead doing "low-value, low return passenger checking".
He argued that the Government should have the "sense and the confidence to focus on who might be a risk".
Clark said that technological advances in border controls, such as the introduction of electronic checking, has improved efficiency and security meaning officials no longer needed to rely on the "old fashioned Civil Service approach of putting process before results".
"It short changes the British public and is a shameful failure to harness the potential of staff, experience and technology," he added.
Clark called on a three-pronged approach to be taken to patrolling Britain's borders that focused on the use of technology, the effective use of frontline staff and an approach based on risk.
"Only by doing all three do we stand any chance on continuing the progress against criminality and terrorism, particularly when resources are being reduced and the number of goods arriving in the UK is dramatically increasing," he said.
Brodie also warned that the Government's plan to introduce a separate border force could threaten security in the run-up to the Olympics.
"The Home Secretary's plans for a separate Border Force outside the UKBA will inevitably take watchful eyes off the security ball as new structures are put in place," he wrote.
Brodie added in his article: "The political kneejerk reaction that suspended risk-based border controls has undoubtedly made it difficult to reinstate this sensible policy. But nothing is surer - it will be reintroduced."
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