Animal rights group Peta’s campaign for the company to stop advertising included 22,000 emails from supporters.

But Peta is urging Thomas Cook to stop sales to the SeaWorld marine park entirely, as it disagrees with SeaWorld’s treatment of orcas and other animals.

Asked about the situation during a media conference call following its Q1 results, Thomas Cook Group chief executive Peter Fankhauser said: “A year ago we introduced a really robust animal welfare policy, taking the Abta standard as the benchmark. We started an independent audit process.

“We did about 50 [audits] and two thirds came out insufficient and we stopped their sale.

“SeaWorld is one of the next we are going to make an audit of, independently.

“If they don’t fulfil the standard of the audit then we’ll stop sale.

“Our clear policy is that we want to improve the wellbeing of all animals in captivity.”

Fankhauser added that Cook is in constructive talks with Peta “because we’re very open to improving our policy”. But added that the company “is not simply following pressure”.

In response, a SeaWorld spokesperson said: “We have been in discussions with Thomas Cook and other tour operators about their animal welfare guidelines and their intention to audit our facilities, and we continue to work collaboratively with them throughout this process.

“SeaWorld parks already operate to the highest animal welfare standards and meet the strict accreditation process of several of the world’s foremost zoological accrediting bodies. We are confident that the world-class animal care and rigorous standards already in place at SeaWorld will meet the Abta guidelines.

“Despite the views of animal activists, who want to see an end to all zoological display, the role of accredited zoos and aquariums is more important now than ever before. Our park guests help us contribute to vital scientific research to assist and fund conservation projects. Alongside other accredited facilities, our aim is to protect marine and terrestrial species for generations to come.”

Elsewhere, asked whether Thomas Cook was likely to follow some major cruise lines and Ryanair in addressing plastic usage, Fankhauser added: “We are in the process of reviewing our whole sustainability policy. We have started with animal welfare and we are reviewing [plastic] as well.”