Airline association Iata has called on the EU to resolve "a looming crisis" over its visa-waiver programmes with the US and Canada.
Iata warns travellers to and from the Schengen area of Europe and North America could be denied visa-free travel from next February.
However, travellers to and from the UK and Ireland, which are outside the Schengen area, would be unaffected.
The issue stems from a so-called 'reciprocity clause' added to Schengen legislation in January 2014.
This means visa-free access to the 26 EU member states in the Schengen area may only be granted to citizens of countries which offer reciprocal visa-free access.
At present, both the US and Canada require some EU nationals to have visas in order to enter.
Citizens of Bulgaria, Romania, Croatia, Cyprus and Poland need visas to enter the US and those of Bulgaria and Romania require visas to visit Canada.
The European Commission is required to enforce the provisions of the 2014 amendment unless the European Parliament and Council advise it not to by a deadline of July 12.
Should the EC enforce the reciprocity requirement, US and Canadian citizens would require visas to enter all EU member states barring the UK and Ireland from February 2016.
The US and Canada would be expected to follow suit in requiring visas of all visitors from Schengen area countries.
Iata regional vice-president for Europe Rafael Schvartzman said: "Nobody wants to risk the economic consequences of new requirements for travellers from Canada and the US.
"We are calling on the EU institutions to agree a proportionate approach."
Supporters of the campaign to remain in the EU have cited visa-free travel as one of the advantages of EU membership and warned of a need to renegotiate agreements if Britain votes to leave.
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