Lengthy queues at Heathrow cleared overnight - but further concerns were raised today about the reputation of the airport with the Olympics on the horizon.
Immigration Minister Damian Green is to be grilled by MPs about the chronic queues, it was announced, after reports of long queues to get past passport control again this week.
Keith Vaz, chairman of the Home Affairs Select Committee, told BBC Radio 4's Today programme: "There is a real problem and the problem has emerged over the last few months.
"I'm not saying we should abandon checks, but it's a choice for the Government - you either look at the way you deal with people when they arrive at Heathrow or you recruit more staff.
"This is not just about the Olympics, this is about what happens before and after, it's about Heathrow as a world-class airport and it's about our reputation, and we need to make sure we get it sorted."
The Labour MP said that queues of more than half an hour were not acceptable.
"I would have thought by the time you get off a plane and you've walked a long way from the plane to immigration, half an hour would be a problem.
"Anything from zero minutes and 30 minutes would probably be acceptable but people would expect to get through much quicker."
A spokeswoman for BAA, which owns Heathrow, said last night's long queues, which saw passengers waiting for up to an hour, had cleared by midnight.
Discussing the situation today, she said: "Everything is looking quite good in the immigration halls. Things are moving and we haven't got major queues.
"The Border Force is putting staff where they are needed at the moment."
Alastair Campbell, the former Downing Street communications chief who was caught up in Thursday night's queues, tweeted: "If this is what Heathrow T5 border queue is like on an average Thursday, Olympic athletes should think about coming soon."
The BAA spokeswoman added: "Immigration is a matter for the Home Office. Immigration waiting times during peak periods at Heathrow recently have been unacceptable and we have called on the Home Office to address the problem as a matter of urgency.
"There isn't a trade-off between strong border security and a good passenger experience - the Home Office should be delivering both."
A Border Force spokesman said: "We will not compromise border security but we always aim to keep disruption to a minimum by using our staff flexibly to meet demand."
No date has yet been announced for Mr Green's appearance before the Home Affairs Select Committee.