Europe-based airlines are starting to resume services step by step as countries try to revive tourism as a way to bring their economies battered hard by the COVID-19 pandemic back to life.

Alitalia, Italy's flagship airline, formally launched long-haul flights from Rome to New York on Tuesday, a day before the country opens its borders to other Schengen countries. The eight-hour flight will run twice a week.

Since early March, the lockdown has all but shut down the airline aside from some cargo flights and a few flights used to repatriate Italians from coronavirus hotspots.

The airline will also restart flights between Rome and the Sardinian cities of Alghero and Olbia on Wednesday, as well as flights between Rome and the Spanish cities of Barcelona on Wednesday and Madrid on Thursday. All the flights will take place with social distancing rules in effect, meaning that flights will be capped at 33 to 50 percent capacity depending on the type of aircraft.

Germany's biggest airline, Lufthansa, announced on Tuesday that it is going to make wearing face masks on board mandatory starting from June 8. This change would initially apply to Lufthansa, Eurowings and Lufthansa Cityline and will preliminarily apply until August 31, 2020.

Lithuania lifted on Monday the 14-day self-isolation rule for travelers from 24 European countries. Travelers coming from Malta, Ireland and Spain remain subject to mandatory two-week self-isolation, while travel is still prohibited from Belgium, Sweden, Portugal and Britain, where the number of COVID-19 patients exceeds 25 cases per 100,000 population.

Up to now, Lithuania has resumed regular flights to Latvia, Estonia, Germany, Norway, the Netherlands and plans to resume flights to Denmark, Israel and Finland in the upcoming week.

From July 1, Malta will reopen its airport for some European countries and Israel. The lifting of restrictions applied only to direct flights, and passengers have to guarantee that they have stayed in the same country for four weeks prior to the flight.

In Cyprus, airports are scheduled to reopen on June 9 when flights are expected to resume with 19 countries considered by Cypriot authorities to be relatively safe as far as COVID-19 is concerned.

Read more: Cyprus pledges to cover costs for virus-hit tourists

As the summer tourism season draws near, the Greek government is preparing to admit tourists from all across the world, but will be adhering to the advice of health experts to ensure it remains a safe destination in terms of coronavirus exposure, the country's tourism minister said Tuesday.

The Ministry of Tourism last Friday announced a list of 29 countries, including China, whose citizens are allowed to visit Greece from June 15.

As of July 1, international flights are allowed into all airports in Greece and visitors are subject to random tests upon arrival, while additional restrictions regarding certain countries will be announced at a later date.

The World Tourism Organization (UNWTO) said on Sunday that there has been a slight easing of world travel restrictions introduced in response to the COVID-19 pandemic, and stressed the importance of international tourism in promoting sustainable economic growth.

"The timely and responsible easing of travel restrictions will help ensure the many social and economic benefits that tourism guarantees will return in a sustainable way. This will contribute to the livelihoods of many millions of people around the world," UNWTO Secretary-General Zurab Pololikashvili said.

On May 7, the organization predicted that international tourist numbers would fall by between 60 and 80 percent in 2020 due to the effects of the novel coronavirus.

(Cover: A departure timetable board displays canceled flights at Brussels Airport in Brussels, Belgium, May 12, 2020. /AP)