Shadow immigration minister Chris Bryant said: "It is time that the Home Secretary came clean about the security at our borders.
"Her cuts to staff have seen passport queues lengthen, not only leading to delays for passengers but also leaving UK Border Force staff with a difficult decision of whether to relax security to alleviate congestion and risk allowing people to enter the UK without being properly checked.
"With a cut of over 5,000 staff promised by the next election, the Home Secretary is leaving our borders dangerously understaffed, just when the UK is expecting record numbers of arrivals for London 2012."
More top news
Chelsea have won the Premier League after beating Crystal Palace 1-0 at Stamford Bridge thanks to an Eden Hazard goal
Craig Charles is quitting Coronation Street after to head back into outer space with Red Dwarf, ITV has confirmed.
The Conservatives have not ruled out increasing tuition fees above the current maximum of £9,000 a year, William Hague has said.