A Border Force spokesman said:
Immigration Minister Damian Green has previously said that last week's problems at Heathrow were mainly due to poor weather - and that it is essential that the UK's borders are secure.
He has also said that all immigration desks at key ports and airports will be fully staffed during peak periods throughout the Olympics.
Christopher Rodrigues, Chairman from VisitBritain:
Shadow Immigration Minister Chris Bryant said:
A PCS Union spokesman said:
New figures show that the Border Force failed to meet its targets for getting non-EU passport holders through immigration at Heathrow last month.
The agency aims to get 95 percent of passengers through within 45 minutes, but at Terminal 5 they only managed 76 percent.
The figures were released on BAA's website after the Government admitted the Border Force needs to change the way it operates. Large queues built up at passport control at the airport last week, with some passengers waiting for up to three hours.
However, the Border Force did meet its targets for EU passport holders, meaning that 95 percent of passengers were processed in less than 25 minutes.
Terminal-by-terminal figures at Heathrow in April 2012 - percentage of non-EU passport holders processed within 45 minutes:
Terminal 1 - 94.5%
Terminal 3 - 87.0%
Terminal 4 - 84.4%
Terminal 5 - 75.7%
Government plans to bring in 80 extra staff to tackle unacceptable delays at Heathrow Airport are like "putting a sticking plaster on a serious injury", a union warned today.
Damian Green admitted the Border Force needs to change the way it operates & said extra staff would start work this month.
But Mark Serwotka, general secretary of the Public and Commercial Services (PCS) union, warned: "Drafting in staff from other areas of an already overstretched agency is like putting a sticking plaster on a serious injury, it will do nothing to stop the inevitable from happening."
Labour said some 1,500 Border Force staff were being cut as the management of Britain's borders drifted "from one shambles to another".
It came as a senior Games boss warned that the delays were damaging the Olympic mission to promote Britain abroad and win business.
BAA, which owns Heathrow Airport, made the following statement:
Long queues had formed at passport control on Thursday and Friday.
The Head of the Border Force, Brian Moore, said that our border controls were generally very efficient.
The Border Force expects most British or European nationals to travel through passport control in 25 minutes or less, and most foreign nationals within 45 minutes.
But occasionally, disruption is caused by issues like flight bunching, where several flights arrive at the same time.
He added: "Occasionally there is some disruption to travelling passengers, which we regret. But we all want a safe United Kingdom and a strong border."
Tom Bates posted this video of the queues at Heathrow Airport on Thursday on Twitter, using the handle @tgdbates.
He wrote: "Outrageous passport queues at Heathrow. Seriously get a grip. How many people in this queue, before the actual queue?!"
Pictures from Tom Bates (Twitter user @tgdbates).