Border checks to catch suspected terrorists and criminals trying to enter the UK through Kent have been suspended almost 100 times in just five years.

The Home Affairs Select Committee, which has been investigating why UK border controls were relaxed without proper authorisation last summer, said it was "shocked" at the number of times key security checks have been scrapped at the Port of Calais.

It found checks against the Home Office Warnings Index (HOWI) - a list of people banned from entering the country - were suspended for health and safety reasons.

Although the Home Office refused to provide the committee with a copy of the HOWI guidelines, it is believed checks can be downgraded to respond to or prevent an emergency such as a fire, overcrowding or, at Calais, queues of vehicles backed up to the motorway.

But the committee's report said: "We are shocked at the sheer number of times the HOWI guidelines have been invoked.

"We are very concerned that the guidance might be being used inappropriately at local level as a management tool instead of an emergency provision.

"Either the number of staff at the border is inadequate to cope with passenger numbers, or senior staff have been too ready to authorise the suspension of HOWI checks, or some combination of the two."

The Home Affairs Select Committee began its investigation after it emerged non-EU citizens were allowed into the UK through the Port of Dover and other entry points unchecked.

UK Border Agency (UKBA) staff were told it was no longer necessary to check the fingerprints of those requiring visas without the approval of ministers.

That revelation led to the suspension of the head of the UK border force, Brodie Clark, who later resigned.

In its report, the committee found a lack of communication between the UKBA and the Home Office, as well as the lack of supervision of staff was to blame.

Keith Vaz MP, committee chairman, said: "Border checks carried out at airports and ports in the UK are the final line of defence against those who should be prevented entry.

"The apparent low levels of supervision at the UKBA are highly troubling. The overuse of the HOWI guidelines and the fact that no one appears to have been aware of what was happening demonstrates a lack of oversight and a failure of communication.

"It's time for a root and branch reform of the way in which the Home Office and the UKBA interact. Only by doing this will we ensure the UKBA is finally fit for purpose."

A Home Office spokesman said: "We thank the committee for their report and we will respond in due course."