The Save our Summer (SOS) – which calls for government to allow overseas travel from May 1 – has amassed 500 members having launched on Monday.

As of Tuesday evening (February 16), 490 travel firms had joined and the group’s Twitter account posted on Wednesday morning (February 17) to say it had passed 500 members.

By joining, travel firms promise to issue refunds or date changes to any customers who book and are affected by government-imposed Covid-19 restrictions that prevent travel.

Companies which added their names to the list in the last 24 hours include Aman Hotels and Resorts, Flight Centre, Kirker Holidays, Sykes Holiday Cottages and Loveholidays.

More than 1,000 individuals have also backed the calls.

SOS co-founder Paul Charles said the “surge” in travel firms signing up to Save Our Summer for a second day proved the group has become “a powerful force across travel”.

“I’m not sure there is any excuse for a firm not to sign up, bearing in mind we are trying to protect jobs and get a re-opening date for domestic and overseas travel,” he said.

The refunds promise comes with the caveat that member operators that have not received refunds from airlines are not obliged to refund in those circumstances – contrary to Abta’s stance on package holiday refunds.

Some operators who had not signed up to the campaign told Travel Weekly they had not done so because they felt this caveat watered down their refunds policy.

Charles, chief executive of The PC Agency, said “the spirit” of the campaign was to refund affected packages in full, but said the caveat was in place because not all bookings would be packages.

“Some are single component and not governed by the Package Travel Directive,” he explained. “There are scenarios where the airline element is non-refundable and the customer is advised that at time of booking.

“Abta guidance is very helpful but not common law. This guidance is regularly updated and followed by members. The [refunds] promise is important as part of giving consumers confidence to book.”

MoreMore than 100 travel firms ‘united in outrage’ launch Save Our Summer