The UK Border Force, the section of the Border Agency that manages entry to the UK, has rejected claims by MPs that the country's airports may not be able to cope with the arrival of thousands of extra passengers for this summer's Olympic Games.
The House of Commons Culture, Media and Sport Committee had warned that planes could be left on runways and there could be long queues at immigration.
"We are well prepared for the Olympics, with additional staff available for busy periods.
"But we will not compromise on border security and are working with BAA to ensure that we are ready to deal with extra passengers."
The wide-ranging Home Affairs Select Committee report showed a fifth of foreign prisoners, some 1,060 criminals, who finished their jail terms in 2010/11 had still not been deported by November last year.
But the Border Agency was unclear over which obstacles were blocking deportation and over which rights more than 520 other foreign criminals who had been allowed to remain in the UK had, the committee said.
It also found that six years after 1,013 foreign nationals were released from prison without being considered for deportation, only 397 have been removed or deported.
The under-fire UK Border Agency must rid itself of its "bunker mentality" or risk raising suspicions that it is trying to mislead Parliament and the public, MPs warned.
Unclear data, which even the agency's own chief executive Rob Whiteman had difficulty in following, can be, at best, confusing and, at worst, misleading, the Commons Home Affairs Select Committee said.
"It is difficult to see how senior management and ministers can be confident that they know what is going on if the 'agency' cannot be precise in the information it provides to this committee," the third damning report of the year into the UKBA's work said.