It was claimed that nine per cent of people who checked their policy and were not covered decided against buying additional insurance.
Helen Warburton, head of Post Office Travel Services, said: "We urge travellers planning to travel abroad for surgery to be honest with their insurance provider about their plans and ensure they are open about any pre-existing medical conditions.
"It's vital to read the small print of travel documents carefully before you travel to ensure you are covered if you need to make a claim."
The British Insurance Brokers' Association recently urged consumers to think carefully about what they need to be covered for when taking out insurance for a break abroad
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