European airline and travel stocks tumbled Monday after Britain reimposed quarantine rules for people returning from France, stoking concern that the spread of coronavirus variants could halt a tourism rebound.

U.K. discount carrier EasyJet Plc dropped as much as 6.5 per cent, British Airways owner IAG SA slumped 5.9 per cent, Ryanair Holdings Plc, which has its biggest hub at London Stansted airport, fell 4 per cent and package-holiday giant TUI AG slipped 4.3 per cent. Air France-KLM was down as much as 4.6 per cent.

The declines were triggered by the British government’s decision late Friday to continue requiring fully vaccinated arrivals from France to isolate amid concern about the beta COVID variant, creating a new category between moderate and high-risk in its “traffic-light” system. As of Monday, inoculated U.K. residents returning from amber nations are no longer required to quarantine.

The “Amber Plus” rule drew an angry response from tourism bodies and airlines, with International Air Transport Association Director General Willie Walsh saying the U.K. “has no coherent policy on international travel.”

The switch, seen as likely to put people off traveling to France, has provoked wider concerns about the status of other amber-list locations that are now quarantine-exempt for double-jabbed travelers and looking forward to the arrival of thousands of Britons to help restore summer earnings.

Britain switched its position on another major holiday market, Spain’s Balearic Islands, earlier last week, moving them back to amber status from green amid concern about a surge in the delta variant of COVID-19 in resorts popular with younger people who may not have had the jab.