The damning report follows comments by the chairman of the Home Affairs Select Committee, Keith Vaz, earlier this month.
Mr Vaz said the number of unresolved cases that UKBA is dealing with - more than 300,000 - is "spiralling out of control".
He said: "There are now about the same number of cases awaiting resolution by UKBA as there are people living in Iceland."
More top news
Chelsea fans are at the centre of a new racism storm after video emerged of supporters mocking the recent racist incident on a Paris Metro.
NASA's Dawn probe is preparing to make an historic rendezvous with the dwarf planet Ceres.
A US Twitter study has found that there are almost 50,000 active pro-Islamic State accounts, but say the number could be as high as 90,000.