The UK’s airline industry warned the government it will not be able to attract future investment as a result of the government’s failure to finalise aviation agreements with the EU in time for March 28.

In a joint letter to Theresa May, the letter’s signatories included representatives from the Aeronautical Engineering Association, Rolls-Royce, Dassault Aviation, Bombardier, the Civil Aviation Authority, the Civil Aviation Craft Mechanism, GE Aviation, Adam Aircraft and the Institute of Aviation.

The letter warned that the lack of an aviation framework will jeopardise job losses in the industry because they cannot plan for Brexit without government support.

“Failure to complete the [sector deal] in a timely manner or in the meantime will set the scene for delays and uncertainty in the final phase of the [sector deal], and further deter potential investment in aviation for the UK,” the letter said.

Noting that the Civil Aviation Authority (CAA) had published a risk assessment that said there were implications for high-profile safety projects involving the CAA and other aviation authorities of a hard Brexit, the letter said: “Such work will need to be placed in jeopardy if a sector deal is not in place.”

The letter was signed by Andrew Richards, EEF’s deputy chief executive; Glyn Gilbert, head of CAA directorate civil aviation; and Greg Fuzel, director general of business aviation at the Institute of Aviation.

Mr Gilbert said that when he recently sat down with Mr Fuzel at an event to discuss aviation, he turned to him and said: “Greg, you know that in aviation nothing happens unless everybody else lets it happen.”

The UK government, which has until March 28 to finalise the sector deal, is not expected to issue fresh guidance on how negotiations have progressed.

The aviation industry welcomed the letter but wanted the government to include a demand that May also legislate as soon as possible for a separate deal, known as a fundamental deal, that would also cover intellectual property, airspace and culture.

Sir David King, former UK prime minister and chair of the Civil Aviation Authority until he died last September, said in July that a fundamental aviation deal should also address “politics and cultural barriers”.