Disgruntled passengers claim they have been stuck in queues at Heathrow Airport for up to five hours and raised concerns about a lack of social distancing.
Photographs show long snaking lines of hundreds of people standing in close proximity - and several MPs are calling for the Home Office to take urgent action.
Families say they have faced some of the longest waits, as children under 12 cannot use e-gates due to limitations with the facial recognition technology.
The delays have been an issue throughout the week for passengers arriving at Europe’s busiest airport, as Border Force staff work to check each passenger is following the Covid travel rules.
The Home Office states there is also a staff shortage, as many Border Force agents are self isolating.
Pictures of people tacked in closely together have sparked fears that Covid will spread like wildfire through those waiting at the airport.
One man reportedly fainted, Mail Online reports, while pregnant women and children were forced to stand in line for hours in order to get through.
“There are massive queues at Terminal 5 again,” one traveller said.
“Really young children and old people had to walk the full walkway as shuttle trains are out of service, and there are no toilets between the gates and passport control.
“No water. No social distancing. Supposedly the UK is a first world country, but not by this measure.”
The Home Office has disputed some passenger claims and said Border Force statistics show the longest queue at Terminal 5 on Saturday was 1 hour and 15 minutes.
In a tweet, Heathrow Airport said: "Whilst we do not have exact figures out how long queues can take our teams in the terminals are on hand to support where possible and we are working with Border Force to reduce delays as soon as possible."
Former Conservative leader Iain Duncan-Smith said: “We are going to achieve the worst of all worlds by having people close together who may have Covid.
“The whole thing is chaotic and we still haven't fully opened up yet. We don't seem to have a plan for how we are going to manage that.
“If it carries on like this Heathrow will cease to be a hub airport and Britain will be left in the backwash as an irrelevant country.”
James Gray, MP for North Wiltshire, said the situation is “totally unacceptable” and it is “deeply embarrassing that the United Kingdom in the 21st century cannot get people into Britain faster than this”.'
Yesterday The Mirror reported a Home Office spokesman previously said travellers "needed to accept" delays due to the summer holiday demand and the requirement to check Covid documents.
The chaos reportedly started on Sunday and has continued every day this week.
People claimed e-gates "stood empty" as they queued up to get through passport control.
One passenger tweeted yesterday: "Chaos at Heathrow Airport Terminal 4. Four hours waiting to go through immigration.
"Families with children, pregnant ladies and old folks everyone had to wait. Is that human?"
Earlier this week, a Home Office spokesman said: "Our utmost priority is protecting the safety and health of the public and we will never compromise on security, and on ensuring passengers are compliant with the current health measures, which means passengers will need to accept an increase in the time taken to cross the border."
