Damian Green, the Immigration minister, faces questioning over the long queues at Heathrow, as fears grow about the airport's global reputation with London 2012 less than three months away.
MPs on the Home Affairs Select Committee will demand to know what caused last week's long delays, with some people arriving from outside the European Union reportedly having to wait up to three hours.
Brian Moore, head of the Border Force, said yesterday that most passengers passed through immigration quickly. "Queues are caused by a number of factors, including incorrect flight manifests or early or late planes which result in bunching," he said. "The important factor is to have staff flexibly deployed in the right numbers at the right times and this is what we always try to do. We are working with BAA to monitor arrival schedules and passenger flows for the rest of the weekend."
He added that the force was "fully prepared" to manage busy periods during the Olympics and would be implementing "well-rehearsed plans". If three- or four-hour queues were "necessary" during the Olympics in light of the risks faced at the time, he told the BBC, then "so be it". "We will not compromise on safety," he said.
He added: "Overwhelmingly, we're doing a good job in balancing getting people through while making sure the border remains secure."
The committee's chairman, Labour's Keith Vaz, said queues of half an hour or longer were not acceptable and that a "real problem" had emerged at Heathrow in the past 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," he told BBC Radio 4's Today programme. "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."
A spokeswoman for Heathrow's owner, BAA, said yesterday: "Things are moving and we haven't got major queues. The Border Force is putting staff where they are needed."
She added: "Waiting times during peak periods at Heathrow recently have been unacceptable and we have called on the Home Office to address the problem... There's no trade-off between strong border security and a good passenger experience: the Home Office should be delivering both."
The date for Mr Green's appearance before the select committee is to be announced.