All travellers arriving in England will be required to take a Covid-19 pre-departure test from 4am on Tuesday, Health Secretary Sajid Javid has said.
In a tweet, the Health Secretary said: "In light of the most recent data we are taking further action to slow the incursion of the Omicron variant."
He also urged the public to get vaccinated, saying "vaccines remain our first line of defence".
Mr Javid said that Nigeria is also being added to the Government's travel red list amid concerns about the spread of the Omicron variant.
"Over recent days we have learned of a significant number of growing cases linked to travel with Nigeria," he told broadcasters.
"There are 27 cases in England already and that's growing. "
From 4am on Tuesday, only UK and Irish citizens and residents travelling to the UK from Nigeria will be allowed to enter, Mr Javid said, and they must isolate in a "managed quarantine facility".
The introduction of pre-departure Covid tests for travellers entering England has been branded a "devastating blow" for travel by the chief executive of the Airport Operators Association.
Karen Dee said that the policy, beginning on December 7, will act as a "major deterrent" to travel.
"This is a devastating blow for aviation and tourism," she said.
"Pre-departure tests act as a major deterrent to travel and most of the limited remaining demand following the reintroduction of self-isolation will now fall away, just as airports were hoping for a small uplift over the Christmas holiday.
"Travel and aviation are the only sectors hit with any operating restrictions in response to the Omicron variant. The UK and devolved governments should have done the right thing and, alongside the restrictions, announced support for our businesses and our staff to get through another period of shutdown."
