The departure of the ninth-largest Atol holder, as of the end of June, means half the top-10 Atol holders operate outside Abta.

"This change allows us to continue providing our valued customers with the protection they have always enjoyed, while also ensuring that we receive better value for our membership fees," a Lasminute.com spokesperson said.

"We believe that Abtot offers a comprehensive range of benefits and services that align more closely with our business needs and priorities."

They continued: "Our primary focus is always to prioritise the protection and satisfaction of our customers, and we are confident that our new partnership with Abtot will further enhance this commitment."

Abta said while it is "naturally disappointed" if any member leaves the association, as a matter of policy it does not comment on individual decisions.

"Abta remains by far the most recognised and trusted travel association brand, which is why our annual renewal rate is typically over 95%, even in a tough economic and competitive environment, and why we continue to welcome new members," a spokesperson said.

An Abtot spokesperson added: "We are pleased that Abtot’s bonding and range of services align with Lastminute’s business needs and priorities, and are delighted to welcome them to Abtot membership."