The government “needs to start an honest discussion” about the consequences of Brexit, according to Abta chief Mark Tanzer, who insisted this has “not happened yet”.

Tanzer said: “We need people to be able to come to this country from the EU to support the tourist economy and businesses.

“But it’s not just about that. When you’re in Brussels, people say ‘You’re not going to have access to markets without regulatory convergence. Tell us what you want.’

“The government is still saying ‘We can have everything’. At a certain point they have to say, ‘OK, we can’t have it’. Whether the government can survive that conversation I don’t know, but it hasn’t started yet. We’re in this Pollyanna world where ‘everything will be fine’.”

Tui UK and Ireland distribution and cruise director Helen Caron agreed: “Customers aren’t aware of some of the impacts that may come down the line.”

However, she warned: “Having that conversation might work against us in the short term. We need to make sure we don’t create more uncertainty.”

Tanzer said he is “more concerned” about Brexit than a year ago, arguing: “We’re closer to people making business decisions and booking decisions.”

He told a Travel Weekly Business Breakfast in London: “The clock is ticking. We need to see some movement.”

Tanzer insisted: “If it was just a business decision, nothing would change. But there is a political dimension that runs alongside the business logic and I don’t think we’ve made any progress in moving the political debate.”

He said: “The core message that we want to keep aircraft flying and be able to move key staff is the one we’ve been carrying to [the UK] government, and to European governments.

“I do think there will be an aviation agreement. Whether we’ll be able to fly to all the places we fly to at the moment is up for negotiation. The sooner we get clarity the better for the industry and for travellers.

“We’re trying to ensure customers don’t lose confidence [and] feel they can book and be able to travel with all the freedoms they have [now].”

Miles Morgan Travel managing director Miles Morgan warned: “If there is one thing that cripples any sector, it is uncertainty. A lack of clarity causes businesses to slow decision making. People want to know what’s happening.

“The quicker decisions can be made the better, but there seems no likelihood of that.”

Freedom of movement of labour remains a major concern, particularly for pan-European businesses.

EasyJet UK country director Sophie Dekkers said: “We’re starting to see European crew wanting to be based in Europe and UK crew requesting to come back to the UK because they don’t know what is going to happen.”

Dekkers also identified a challenge for the UK Border Force “if people aren’t able to get through passport control as easily”.

Caron said: “Freedom of movement for our representatives and for our ships’ crew is important. We’re considering all alternatives and scenarios.”