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."
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Cloud and outbreaks of rain will ease away eastwards during the morning, clearing the east coast around midday with sunny spells developing.
Police and emergency services are attending the scene.
Rebel-held east remains at risk while the pumping station supplying the western part of the city is once again in operation.