The UK has extended its advice against all non-essential travel to Spain to include the Balearic and Canary Islands after a rise in coronavirus cases.
Foreign Office guidance was changed on Monday to include both mainland Spain and islands such as Ibiza and Tenerife.
It came as a government source said talks were under way with Spain to provide a quarantine exemption for those returning from the islands.
The advice is in addition to the self-isolation policy that began on Sunday.
Travellers returning to the UK from anywhere in Spain must now self-isolate for 14 days at a registered address.
A Foreign Office spokesman said: "We have considered the overall situation for British nationals travelling to and from the Balearic and Canary Islands, including the impact of the requirement to self-isolate on return to the UK, and concluded that we should advise British nationals against all non-essential travel to the whole of Spain."
Speaking earlier, Boris Johnson's official spokesman warned "no travel is risk-free during this pandemic".
The rate of infection in Spain is 35.1 cases per 100,000 people, while the UK is at 14.7, according to the latest figures from the European Centre for Disease Prevention and Control.
Data up to 19 July suggested there were lower rates of infection in the Balearic and Canary Islands than in mainland Spain.
Among the thousands of British holidaymakers affected by the change to quarantine rules was Transport Secretary Grant Shapps, who flew to Spain on Saturday despite knowing a decision on the policy was due.
Mr Shapps said in a statement he would return to the UK this week in order to complete his quarantine and would return to work as soon as possible.
Holiday firms Jet2 and Tui announced sweeping cancellations following the new quarantine rule for arrivals back into the UK from Spain.
But airlines EasyJet and Ryanair said they would continue to operate full schedules of flights to Spain.
The UK imposed the restriction over the weekend after a spike in infections in some Spanish regions, including Catalonia, where Barcelona is located, and Aragon.
The French government has been telling its nationals to stay away from Catalonia, while Norway has imposed a new 10-day quarantine on all travellers arriving from Spain.
A further seven people with coronavirus have died across all settings in the UK, according to latest government figures - bringing the UK's death toll to 45,759.
The government also said in the 24-hour period up to 09:00 BST on Monday, there had been a further 685 lab-confirmed cases. The UK's total is 300,111.