The European Commission has said that any vouchers offered to consumers in lieu of cash for cancelled flights should be voluntary and transferable.
The advice is part of a plan to help revive travel and tourism across the bloc.
It has issued guidance on how to safely resume travel and reboot Europe's tourism in 2020 and beyond.
It says member states should gradually lift travel restrictions and allow tourism businesses to re-open, while respecting necessary health precautions.
"As soon as the health situation allows, people should be able to catch up with friends and family, in their own EU country or across borders, with all the safety and precautionary measures needed in place", it says.
It says that as states reduce the circulation of the virus, blanket restrictions to free movement should be replaced by more targeted measures.
But if a generalised lifting of restrictions is not justified, the commission recommends a phased and coordinated approach of lifting restrictions between areas with comparable situations.
It says the approach must also be flexible, including the possibility to reintroduce certain measures.
On the use of vouchers for affected travel plans the commission says under EU rules, travellers have the right to choose between vouchers or a cash reimbursement.
It explains: "While reaffirming this right, the commission's recommendation aims to ensure that vouchers become a viable and more attractive alternative to reimbursement for cancelled trips in the context of the current pandemic, which has also put heavy financial strains on travel operators.
"The voluntary vouchers should be protected against insolvency of the issuer, with a minimum validity period of 12 months, and be refundable after at most one year, if not redeemed."
It says any such vouchers should also provide passengers with flexibility, and allow them to travel on the same route under the same service conditions.
And it says they should also be transferable to another traveller.
The Government announced a scheme last week that would see travel agents given the option of providing a credit note, guaranteed by the State, to customers in lieu of refunds.
The EU package also aims to help the tourism sector recover from the pandemic.
The guidelines have general principles for the safe and gradual restoration of passenger transport by air, rail, road and waterways.
These include the need to limit contact between passengers and transport workers, and passengers themselves, reducing, where possible, the density of passengers.
It has also set out a framework to gradually restore tourism activities.
The commission says these guidelines will allow people to safely stay at hotels, eat and drink at restaurants, bars and cafés and go to beaches.
And it says any tracing apps to track the coronavirus used by member states should be cross-border.
It says: "Such tracing apps must be voluntary, transparent, temporary, cybersecure, using anonymised data, should rely on Bluetooth technology and be inter-operable across borders as well as across operating systems.
"EU citizens must be able to receive alerts of a possible infection in a secure and protected way, wherever they are in the EU, and whatever app they are using."
The commission adds that it is supporting member states in finding the right solution.
Travel, transport, accommodation, food, recreation or culture contribute to almost 10% of EU GDP.
Tourism has also been one of the most affected by the heavy restrictions on movement and travel.
The World Tourism Organisation (UNWTO) has said it expects a 20% to 30% reduction in international arrivals, amounting to losses of between €280 and €420bn for the travel industry worldwide.
In Europe, the summer is a crucial season for the industry - bringing €150bn on average.
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