Chris Rowles, the association’s chairman, said the move to put Portugal on the amber list from next week “did not make sense” and would damage consumer confidence in booking overseas travel.

“It will bring the tiny number of bookings that have been coming in daily to a juddering halt,” added Rowles. “It will also create even more confusion and a demand for refunds, which customers will not be entitled to should they decline to travel.

“If no travel businesses are going to be allowed to trade this summer, after 15 months of zero income and considerable cash outflow, there is now one key thing the government needs to deliver to operators, agents and others: the long-overdue sector-specific support that government has squirmed out of delivering to date.”

The government has so far resisted calls for sector-specific financial support for the wider travel industry, although some money has been provided to support aviation.

Rowles added: “Our message is crystal clear: pay up prime minister, chancellor and fellow ministers, without delay. Tour operators and travel agents need significant sector-specific payments, and we need them quickly.”

Abta chief executive Mark Tanzer also repeated the call for “tailored financial support” due to travel’s slower recovery than other sectors of the economy.

“Travel companies are desperately worried that, at a time when the market hasn’t opened up, they will shortly face increased furlough and business rates costs, with support being gradually withdrawn from the end of this month,” added Tanzer.

“It’s vital that the government doesn’t leave these businesses behind as it focuses on the domestic unlocking.”

Julia Lo Bue-Said, chief executive of Advantage Travel Partnership, said the trade was having to deal with a government which “seems to have forgotten its travel industry exists”.

“We have been clear from the outset that countries falling off the list at short notice creates anxiety, confusion, dents consumer confidence and throws up huge operational challenges for travel agents and the industry,” she said.

“As an industry we have collectively asked for a clear line of communication from government, including transparency over the data. We are still not receiving timely, relevant information to support businesses on the brink of survival.”

Lo Bue-Said added the government needed to support the industry “instead of demonising international travel with unnecessary barriers, complexities and costs”. 

John Bevan, divisional senior vice president at dnata Travel Group, said the latest green list decision “will mystify the travel industry”. 

“You begin to wonder what other agendas are in play, when decisions taken contradict the very criteria we and our customers were presented with just a few short weeks ago,” asked Bevan.

“Our industry, which is worth billions to the UK economy and employs thousands, cannot go on with this uncertainty and unpredictability indefinitely.

“Targeted support for what were well-run businesses has to be forthcoming. If the government is determined to pull the rug out from under the industry like this, then it has a duty to help break the fall.”