A new testing scheme designed to reduce the quarantine period for people arriving in England has suffered what has been described as a "chaotic start".
Launched on Tuesday, the scheme offered travellers the chance to cut the 10-day self-isolation by paying to take a coronavirus test after five days, and receiving a negative result.
But it emerged that a number of the 11 testing firms on a government list published on Monday night were having trouble providing the "test to release" service.
One of them, SameDayDoctor, asked to be withdrawn from the programme.
It posted a message on its website saying: "Unfortunately we have been so overwhelmed with requests for test and release that we cannot answer any more emails nor take any more bookings."
Axiom Laboratory said the service was "not yet available", Halo Verify said tests were out of stock and Medicspot was not accepting new orders due to a backlog.
The quarantine rule applies to people arriving from overseas locations except for those on the government's travel corridors list.
The Department for Transport announced the new programme three weeks ago, offering a glimmer of hope to a travel sector battered by the coronavirus crisis.
Yet the plan attracted immediate criticism from the likes of Ryanair's boss Michael O'Leary, who complained there had been a lack of consultation with the industry.
There was further anger from the sector at the scheme's troubled start.
Paul Charles, chief executive of travel consultancy The PC Agency, told the PA news agency: "It's a chaotic start for a system that was flagged as a solution to recovery in the travel sector, but it's been weeks in planning and has taken minutes to fall apart."
Richard Burge, chief executive of the London chamber of commerce, said the failure "defies belief" with the return of travel and tourism critical to the capital and the UK's economic recovery.
He said: "The government must urgently remove its selected providers who have fallen at the first fence and add those that can and already are providing testing services at our airports.
"This is another example of government doing things to business rather than with business."
Shadow home secretary Nick Thomas-Symonds said: "This vital service appears to be descending into chaos.
"The Conservative government has had months to get this system right. They urgently need to get a grip."
The prime minister's official spokesman said: "We have already secured 11 testing providers that meet our minimum standards and are working at pace to secure more."
