LONDON: Tour operator TUI has cancelled all British holidays to mainland Spain from Monday until August 9, after the UK government's decision to require travellers returning from the country to quarantine.

The newly-imposed rule to self-isolate, abruptly introduced at midnight Saturday hours after being announced, follows a surge in coronavirus cases in parts of Spain in recent weeks.

Other major British airlines have so far held off cancelling flights to Spain.

TUI, Britain's biggest tour operator, said its decision did not apply to the Balearic Islands and Canary Islands, where Covid-19 case numbers are markedly lower than in parts of mainland Spain. Meanwhile holidaymakers already in the country will still be able to take their original flight home.

German-owned TUI said customers impacted by the cancellations would be able to receive a full refund or the option to rebook their holiday.

The operator said it was in contact with Britain's Foreign Office "to understand" why the government has introduced quarantine measures for all of Spain, when its travel advice is less stringent for the Balearic Islands and Canary Islands.

"We believe regional travel corridors need to be considered," it said in a statement.

"The UK Government must work closely with the travel industry as this level of uncertainty and confusion is damaging for business and disappointing for those looking forward to a well-deserved break."