Heathrow queues: Border Force 'ready' for Olympics
The UK Border Force says it is "fully prepared to manage busy periods" such as the Olympics despite criticism over recent delays at Heathrow Airport.
Border Force chief Brian Moore said security would not be compromised but staff would be "implementing our well-rehearsed plans" in July and August.
MPs have said the UK's image was being tarnished and called on Immigration Minister Damian Green to explain.
Non-EU passengers have spoken of three-hour queues at Heathrow Terminal 5.
The longest delays were reportedly seen at passport control on Wednesday, but queues have also been seen over the past month, with some UK and other European Economic Area passengers said to have experienced waits of up to an hour - more than double the 25-minute "service standards" target set by the Home Office.
In March, following revelations that hundreds of thousands of people were let into the country without appropriate checks, the home secretary announced that the UK Border Force would be split away from the UK Border Agency and become a separate entity.
But Lucy Moreton from the Immigration Services Union said there were now too few staff on duty.
"There simply is no way to deliver the 100% secure border that we are required to deliver with the number of staff we have left," she said.
Mr Moore told the BBC News Channel the Border Force aimed to keep disruption to a minimum but "would not compromise on the safety and security of the UK".
"Overwhelmingly we are doing a good job on balancing getting people through whilst making sure the border remains secure," he said.
Mr Moore said: "The vast majority of passengers pass through immigration control quickly.
"Queues are caused by a number of factors, including incorrect flight manifests or early or late planes which result in bunching.
"The important factor is to have staff that are flexibly deployed in the right numbers at the right times and this is what we always try to do."
MPs on the Home Affairs Select Committee say they plan to question the immigration minister about the issues in May.
Committee chairman Mr Vaz said: "If you arrive at Heathrow and you see half the kiosks empty and you are waiting for three hours, that's simply not acceptable."
Earlier, the Labour MP told BBC Radio 4's Today programme, a "real problem" of delays at immigration controls had emerged in recent 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."
BAA said queues at Heathrow Airport passport control on Friday evening cleared by the morning.
But it has called on the Home Office to "address the problem as a matter of urgency" and has described the queuing seen at airport immigration control as "unacceptable".
A BAA spokeswoman said: "There isn't a trade-off between strong border security and a good passenger experience. The Home Office should be delivering both."