Airlines, holiday companies, tourists and vast swathes of southern Europe are looking forward to hearing the UK's plan to relaunch travel but only a limited number of countries are set to be declared safe to visit.

Britain's biggest destination countries including mainland Spain and Greece, as well as France, all risk being excluded from the initial "green list" for quarantine-free travel expected on Friday. After a year of restrictions, that would be a major blow for tourist hotspots and the airline and holiday companies which are all desperate for big-spending Britons to travel.

British Airways, easyJet, Ryanair, TUI and others will likely have to wait until at least late June for a larger scale re-opening of UK travel needed to repair their COVID-19 battered finances. Most travel from the UK has been banned since the beginning of the year due to pandemic restrictions.

The British government has said people from England can go abroad again from May 17 at the earliest, and more clarity is expected on Friday on the traffic light system which will grade countries green, amber or red based on their COVID-19 risk. The green list is likely to comprise smaller destinations such as Gibraltar, Iceland, Israel and Malta, while bigger markets like Portugal and the United States also have a chance. Some analysts suggest that certain Greek islands like Crete and Rhodes, and Spain's Canary Islands could feature.

EasyJet Chief Executive Johan Lundgren told an online conference on Thursday that Britain risked being left behind by the rest of Europe if the green list was small. While Britain's vaccination programme has outpaced the rest of Europe so far, the EU has already outlined its travel plans, recommending the arrival of foreign travellers from more countries from June.

However limited Britain's green list, the travel industry will hope that clarity on destinations will boost bookings, and that some customers will travel to amber countries, despite the requirement for 10 days of self-isolation on return. Green list travel will involve people taking two COVID-19 tests, one before arrival back into the UK and one within two days of returning.

Airlines and travel companies have complained that the high cost of tests - at around 100 pounds ($140) each -- will dampen demand, but testing prices are falling as competition picks up. TUI on Thursday announced testing packages starting at 20 pounds for its UK customers travelling back from green countries.

Britain has promised to reassess its travel plans before June 28 and said that the allocation of countries will be kept under review. The industry is hoping for a review of a country's category every three weeks.