Analysis of 199 travel policies from 71 providers found that just six in 10 (120) provided cover if travellers have to cancel a trip due to strikes.

That means four in 10 did not provide cover for cancellations as a result of strike action, while for one policy, it was an optional extra, the Which? annual review revealed.

The consumer champion also found there are huge disparities in the level of Covid cover at a time when cases are on the rise.

It found less than one in 10 of the 199 policies examined offer ‘complete’ protection in the event of a holiday being disrupted by Covid.

This means travellers can claim for emergency medical care if they catch Covid abroad, and have the option to claim cancellation costs if they test positive for Covid before their trip.

Further, these policies also cover self-isolation if it is made a legal requirement. And claims could be made if the Foreign, Commonwealth & Development Office advises against travel to a destination because of Covid or because of regional or national restrictions on movement.

It rated three in 10 policies (55) as ‘low’ for Covid cover as they provided emergency medical cover for contracting Covid abroad and the ability to claim if cancelling a trip due to testing positive.

And four policies were deemed ‘basic’ as they only provided emergency medical cover in the event of catching Covid abroad.

Which? reminded travellers that if their holiday is cancelled by a package tour operator, they are legally entitled to a refund. And when it comes to cancelled flights, airlines are obliged to refund passengers, including when it is due to staff going on strike.

For those with an ATOL protected package holiday, it means travellers will be reimbursed if the company goes out of business, and provides repatriation for those who are abroad at the time.

The consumer champion also advises that holidays are bought on credit card where possible. This is because credit card providers are legally bound to reimburse customers who have made purchases over £100 and where there is an issue such as the good or service not being as advertised or a company failing to provide a refund.

‘Levels of cover can vary wildly’

Jenny Ross, Which? Money editor, said: “With many airlines warning of widespread disruption this summer and Covid cases on the rise, travellers should ensure they’ve taken out adequate insurance to cover any losses or unexpected costs they might face.

“Which? analysis of 199 policies shows that levels of cover can vary wildly in important areas like disruption caused by strike action or Covid.

“We advise travellers to always check policies carefully to ensure they offer the cover that will be most appropriate to their trip, and to ensure they have cover in place from the time of booking.”