The head of Delta Air Lines has expressed frustration with the closure of the US to European visitors, which he said had left transatlantic travel a “one-way” market despite the government being given “all the science why it’s safe”.

Airline executives in the US, UK and Europe have lobbied for months for an end to restrictions on international travel. Some European countries have begun admitting US citizens who can show proof of vaccination or a negative Covid-19 test, but most UK and European visitors remain banned from the US.

“The international markets where US vaccinated travellers can go, particularly in southern Europe, we’ve had really strong booking interest,” said Ed Bastian, Delta chief executive.

“The problem is those markets are only one-way. The White House specifically is not willing to open up the US marketplace to European or UK travellers, which is a source of frustration.”

He added: “We have given them all the science why it’s safe . . . but the White House is still concerned with the overall vaccination rate in the country.”

The Delta variant of Covid-19 has made it difficult to predict when international travel would return at scale, Bastian said. Routes to Asia are likely to take a year to reopen, with South America off-limits for another six to 12 months and the UK and Europe until early autumn.

Delta’s second-quarter results showed that transatlantic travel is still taking a battering, with the airline reporting $288m in revenue from those routes, an 85 per cent drop compared with the second quarter of 2019. Revenue from passengers flying in the US fell 45 per cent to $4.5bn.

The Atlanta-based airline reported pre-tax income of $776m, its first profit since the pandemic gripped the aviation industry in March 2020. The figure included $1.5bn from the second and third rounds of the Payroll Support Program that the US government established to avert furloughs. Without the taxpayer funding and certain adjustments on investments, Delta reported an adjusted pre-tax loss of $881m.

US travellers returned to the skies in greater numbers in the second quarter, encouraged by the increased availability of vaccines. Delta’s adjusted second-quarter operating revenue of $6.3bn was up 76 per cent on the first three months of the year, but still down 49 per cent on the second quarter of 2019.

Corporate travel has also rebounded. In March, the volume of corporate travel had only recovered 20 per cent of pre-pandemic levels but in June, as offices began to reopen, the figure reached 40 per cent. Bastian said he expected it to rise to 60 per cent in the autumn.

The airline brought in $1.8bn in revenue from business and first-class travellers during the quarter, down 56 per cent from two years earlier.