More needs to be done to deal with lengthy queues at Heathrow Airport's immigration desks, Prime Minister David Cameron has said.
Mr Cameron said he was "still not satisfied" at the level of queues at Heathrow and other airports despite extra staff being drafted in during the Olympics.
He said he wanted quick results this week and next to "get on top of the problem" of queues of up to three hours, which Labour claimed is the result of cutbacks in staffing levels at the UK Border Agency.
Speaking during Prime Minister's Questions in the Commons, Mr Cameron said: "In terms of Heathrow and our airports, I think it is vitally important that we continue to make progress.
"This is an urgent issue for Britain. It is vital for our trade, it is vital for inward investment that people have a decent experience when they arrive at our airports.
"We have got a new control room opening at Heathrow this month, there are an extra 80 staff for peak times at Heathrow, an extra 480 people will come on stream during the Olympic period.
"But I am still not satisfied. We need to do more, including more this week and next week to really get on top of this problem."
Mr Cameron's comments came after Labour MP Keith Vaz, chairman of the influential Commons Home Affairs Select Committee, said officials at the UK Border Agency should never have split a bonus pot of £3.5 million when there had been such problems at immigration desks.
In a question to the Prime Minister, Mr Vaz said: "Given the horrendous queues at our airports, the fact that 100,000 files have now been archived by the UKBA, and 185 people have absconded in the last six months having been given limited leave, can I ask you, do you agree that in future we should be rewarding success not failure?"
Mr Cameron added: "There is absolutely no place in the modern civil service for the presumption of good performance. I do believe in actually paying people bonuses if they perform well and meet their targets. But if they don't perform well and don't meet their targets, they shouldn't get a bonus."