UK health officials are reviewing private Covid-19 testing companies ahead of the country's ban on international travel being lifted.
All testing firms on a government list to be given to travellers were called into video meetings this week amid fears the system could collapse when widespread non-essential travel resumes.
The companies were questioned about their capacity and told they face removal from the lists if they can't deliver the tests on time, The Times reported.
Under the government’s traffic light system, which begins on Monday, those from green list countries are required to order one PCR test to take within two days of arrival.
People coming from amber countries should order a test for day two and day eight of their 10-day quarantine period, although there is the option of early release after taking a test on day five.
Travel from red list countries remains banned for leisure purposes, with those that do have to travel required to pay £1,750 to quarantine in a government-approved hotel.
The private tests are purchased independently of the free scheme offered by the NHS.
Operators do not have a contract with the government but are listed alphabetically on its website.
An investigation by consumer advocate Which? found thousands of travellers had complained about not receiving the tests on time, despite paying hundreds of pounds.
Some passengers were forced to extend their quarantine as the tests failed to arrive in the post.
The government list says some companies are charging travellers as much as £549 ($770) for the tests, despite the regular price being about £200.
The government is said to have told the companies they would be monitored against benchmarks, including customer service and turnaround times.
To appear on the list, companies need to declare they meet certain standards and basic checking is completed by the UK Accreditation Service. They are allowed to remain on the list until the full accreditation process is complete.
The Department of Health said it took “rapid action” against providers that didn’t meet the requirements.
“In the first instance, they will receive a warning and are given five days to demonstrate they have addressed concerns, and if not, they are removed from the gov.uk list,” it said.