Britain's borders were left exposed to terrorists last year after a Home Office computer system which screens passengers crashed twice in 48 hours, The Telegraph can reveal. 

The eBorders system, which was put in place after the 9/11 terror attacks to protect the country from jihadists, ground to a halt in June last year, The Telegraph reported on Thursday.

The incident, which this newspaper has seen details of, was deemed so serious that Theresa May, the Home Secretary, was alerted by officials close to midnight. 

The Home Office refused to reveal how often the system has crashed or whether there have been any outages since the incident. 

Technicians worked through the night to fix the system amid fears from border officials that hundreds of extremists, convicts and illegal immigrants were arriving in the UK undetected.

The disclosure that a vital part of Britain’s border security stopped working during a time of “severe” threat from terrorism will raise serious questions about whether it is fit for purpose. 

May is likely to come under pressure to explain why the public were kept in the dark despite tens of thousands of people likely to be traveling into the UK at the time. 

Flights were not grounded despite the system being down and border officials unable to check in advance passenger details against terrorism watch lists. 

However the warnings index – which dates back to 1995 – was deemed inadequate on its own after the 9/11 attacks and was recently found to be breaking down twice a week. 

But terrorists or criminals could still have boarded aircraft without being detected by British security services. 

The Telegraph has launched a new Border Security campaign, which has seen former counter terrorism figures call for a review in the wake of terror attacks on the Continent. 

At the heart of Britain’s ability to stop dangerous people entering the country is Semaphore, a system which checks passenger data against watch lists of suspect individuals. 

Every day Semaphore scans information on passengers traveling to and from Britain on planes, trains and ferries against lists of those flagged up by government agencies. 

The system - unlike its predecessor - helps alert the border agencies to suspect passengers bound for the UK before they board planes.

Source : MENA