Travellers arriving in the UK from Uruguay, Namibia and the US Virgin Islands will have to self-isolate, the government has said.
The changes will be effective from 4am on Saturday.
Transport Secretary Grant Shapps said there will be no further travel changes for two weeks over Christmas, unless an emergency decision has to be taken amid a major spike in coronavirus cases abroad.
He tweeted: "Latest data means we must remove URUGUAY, NAMIBIA and US VIRGIN ISLANDS from the #TravelCorridor list. From 4am Saturday 19 December, if you arrive into the UK from these destinations you will need to self-isolate.
"Providing certainty to those travelling over Xmas, we will only make EMERGENCY removals to the #TravelCorridor list if needed for the next two weeks. Next regular update 7th Jan."
The new system meant that inbound passengers forced to quarantine could cut their self-isolation period from 10 to five days if they get a negative test result from a list of private providers.
But on Tuesday, the day the scheme was due to launch, a number of the 11 specified testing companies said they were unable to provide the service.
A Department for Transport spokesperson told Sky News that "teething issues have been ironed out" since then and "overall capacity is looking very positive".
Last week, the Canary Islands were removed from the UK's "safe" travel list.
The Spanish islands were only added to the travel corridor list in October, resulting in a surge in bookings.
People in England, Wales, Scotland and Northern Ireland are allowed to travel between the four nations during the "Christmas bubble" period of 23 to 27 December.
Wales First Minister Mark Drakeford said only two households can mix indoors by law over the festive period - instead of three in the rest of the UK.
And on Wednesday, Prime Minister Boris Johnson urged people not to travel if possible, with his chief medical officer Professor Chris Whitty telling people to "stay local".