The Irish Government has agreed to continue the ban on British travel until midnight on Friday January 8, Transport Minister Eamon Ryan has said.
From Saturday January 9, all passengers coming from Britain and South Africa will be required to possess a negative PCR test acquired within 72 hours of travelling.
Mr Ryan said: "They will have to present that negative test at the border management unit at an airport or at the ferry terminal.
"Failure to do so will be subject to either a fine of 2,500 euro or up to six months imprisonment penal provision, to make sure we get compliance."
The provision is certain to remain in place until at least January 31, he said.
He added: "We expect other countries to be doing something similar and we'll work in co-operation with other countries, and with the European Commission, to monitor and manage how this affects individuals.
"The Cabinet's agreed provisionally to apply the same measures to other jurisdictions, other red-list countries.
"We will work first of all introduce to the UK provisions, and we will work in the next week with European Commission and others, people involved in the travel industry, in terms of how we broaden and apply the same measures too from other jurisdictions."
It comes as the Cabinet agreed a raft of new tight restrictions as the virus spreads throughout communities across the Republic, including closing schools except to Leaving Cert students who will attend three days out of five.
