The UK has launched a review to cut the number of people exempt from travel quarantine in an attempt to tighten the borders against Covid-19.

Priti Patel, home secretary, said ministers would “urgently” revise the list of exemptions “so that only the most important and exceptional reasons are included” among those that do not have to quarantine.

There are certain key professions — that includes diplomats, elite sports people and nuclear engineers — who can enter the country without needing to self-isolate on arrival. Some of those workers do not even need to take the pre-flight Covid-19 test which was made compulsory for most people in recent weeks.

People needing to travel for medical emergencies are also on the exemption list.

Ms Patel announced that anyone wanting to leave the country would have to declare the purpose of their journey before setting off.

“Anyone who does not have a valid reason for travel will be redirected home,” she announced in the House of Commons. “There are too many people coming in and out of our country each day.”

The number of arrivals into the UK has fallen by about 98 per cent compared to before the pandemic but there are still about 13,000 people coming in daily, according to the travel industry.

The government loosened the list of quarantine exceptions in December to include categories such as journalists, film directors and performing arts professionals, but it removed them from the list a week ago.

Meanwhile, Ms Patel confirmed that new arrivals from more than 20 high-risk countries will have to spend their 10-day quarantine in a hotel — at their own expense — under the new rules, as reported in the Financial Times on Monday.

Ms Patel told the Commons that UK residents coming home from countries currently covered by a travel ban — including Brazil, Portugal and South Africa — will have to self-isolate in a hotel. Non-UK residents are already banned from travelling to Britain from those countries.

The home secretary, who has fought for tougher border controls since the start of the crisis, had argued in recent days that the borders should be closed while the government prepares a blanket hotel quarantine scheme for all entrants.

But she was overruled at a meeting on Tuesday evening of the “Covid-O” committee by Boris Johnson, prime minister, amid concerns about the economic consequences of the move.

Grant Shapps, transport secretary, and foreign secretary Dominic Raab were among those who argued against total closure of the borders to prevent further damage to the travel industry.

However, Mr Johnson will reserve the right to force all arriving passengers to self-isolate in hotels — paying the £1,000-plus cost themselves — in the future.

The prospect of tighter restrictions in the near future has prompted alarm among the bosses of the UK’s leading airlines, who on Wednesday warned their businesses needed an “urgent road map” out of tightened travel restrictions.

In a letter to Mr Johnson, 11 chief executives — including the bosses of British Airways, easyJet and Virgin Atlantic — wrote they had seen “no compelling scientific evidence” to force all arrivals into state-supervised quarantine.

“UK airlines cannot survive a second summer season without meaningful revenue, or additional support,” they wrote in a letter seen by the Financial Times.

The effective closure of the UK border would also affect freight and PPE supplies being brought in by air, the industry leaders warned.

Ministers are set to keep the “test and release” programme under which entrants into England can end their 10-day quarantine early if they record a negative Covid-19 test after five days of arriving from a safer “green list” country. Ms Patel also said the police were increasing checks on those meant to be self-isolating after entering the country.

The action from the UK comes as countries across Europe move towards tighter travel restrictions, including in Germany where the government this week said it was considering tougher curbs on air travel.

Nick Careen, a senior executive at Iata, the airline industry’s trade body, said he was concerned over the “widespread movement” towards grounding aircraft.

“There is a way to manage international traffic and not make it the scapegoat it is being portrayed at the moment,” he told reporters at a press conference on Wednesday.