Heathrow airport has warned that "significant gaps remain" ahead of the government's launch of quarantine hotels from Monday.
The move will see travellers entering Britain from COVID-19 hotspots having to quarantine for 10 days in government-managed hotels, and at the travellers' expense.
The new quarantine system will mean British and Irish residents returning from 33 "red list" countries will have to pay £1,750 to quarantine in hotels for 10 days, and passengers could ultimately face 10 years in prison if they attempt to conceal having recently been to one of these countries.
Passengers will have to book their hotel online before travelling, with the £1,750 fee including the cost of being tested for coronavirus, as well their escort between the airport and their designated hotel, plus food, accommodation and security.
When passengers arrive they will be escorted to a designated hotel, which will be closed to guests who are not quarantining. The government said it had booked 4,600 rooms across 15 hotels to house these passengers.
But a spokesperson for Heathrow has called on the government to ensure that there are "adequate" resources and "appropriate protocols in place" to handle the passenger journey from the aircraft to the hotel.
In a statement, they said: "When the government announced its hotel quarantine plan, we immediately offered our help to make this successful in a complex airport environment.
"We have been working hard with the government to try to ensure the successful implementation of the policy from Monday, but some significant gaps remain and we are yet to receive the necessary reassurances.
"We will continue to work collaboratively with government over the weekend but ministers must ensure there is adequate resource and appropriate protocols in place for each step of the full end-to-end process from aircraft to hotel to avoid compromising the safety of passengers and those working at the airport."
The statement follows the online booking system that passengers are expected to use suffering technical problems within hours of going live, leaving some users unable to use the new online portal, instead facing a message that it was undergoing "maintenance" until 3pm on Thursday.
A Department of Health and Social Care spokesperson explained: "Rooms are available from Monday 15 February and travellers will be able to book through the site imminently. The website is undergoing maintenance to correct a minor technical issue."