The consumer group looked at 263 travel insurance policies and found just two – HSBC Select and Cover and Barclays Travel Pack – offered full protection.

They cover travellers against: cancellation due to changes in government advice or lockdowns prohibiting travel; testing positive for Covid or being told to self-isolate; and medical costs and repatriation.

A further 85 policies were ranked ‘superior’, providing cancellation cover for travellers having to self-isolate without a positive test, but not for government advice changing.

Meanwhile, 34 policies were ranked ‘basic’, meaning they provide travellers with cover for Covid-related emergency medical costs and repatriation, but not for cancelling a trip if a traveller contracts Covid. Direct Travel, esure and Sheilas’ Wheels were among the well-known providers offering ‘basic’ policies.

Which? is calling for the government to work with regulators to ensure all travellers adequately understand their travel insurance cover.

Last month, the consumer group warned many travel insurance customers were being left with a false impression about the level of protection they would benefit from if the pandemic was to impact on their holiday plans.

It wants travel and insurance providers to give travellers clear information about their policies, including those relevant to cancelled flights, changes in travel advice and refunds, and clearly highlighting the policies’ limitations.

It said the Financial Conduct Authority should monitor how well insurers are presenting this information.

Gareth Shaw, head of Which? Money, said: “As the removal of Portugal from the green list shows, last-minute disruption to holiday plans can happen – and our research shows that many travel insurers don’t offer much protection if it does.

“The government should work with regulators to ensure that travellers, should they choose to go abroad, are given clear information about what they will and won’t be covered for – and make sure that providers don’t make bold and confusing claims about their cover without being clear about the limitations.”