By Bob Howard
BBC Radio 4's Money Box
The popular beaches of Mexico are empty following the flu outbreak
Travel insurers refusing to compensate people for not travelling to Mexico are acting unreasonably, Holiday Which? has said.
Some holidaymakers following Foreign Office advice not to travel because of swine flu have found they cannot claim.
They are normally offered alternative destinations or dates by their airline or travel company.
But some customers say they only want to go to Mexico and should get their money back.
The travel industry estimates as many as 30,000 British holidaymakers had planned to go to Mexico in April.
Jack from London was due to fly there for his honeymoon.
When he heard the Foreign Office was advising against non-essential travel to Mexico, he hoped he would get a refund on his flight and hotel, which he had booked separately.
But his hotel would only give him half his money back and the airline agreed to offer him an alternative destination but refused to refund him at all.
When he checked his travel insurance, he was told he was unable to claim because his company did not cover holiday cancellations due to changing Foreign Office guidelines.
In the end Jack paid for another flight and hotel for his honeymoon so he could go to a place of his choosing.
He does not understand why his insurer refused to pay out.
"I was a bit surprised because I thought that's exactly the sort of thing travel insurance would be there for," he told BBC Radio 4's Money Box.
Which? Holiday says travel insurers are wrong to put these exclusions in their policies.
Rochelle Turner, head of research at Which? Holiday, believes travellers should not be punished for following government advice.
"I think it's entirely unreasonable. I think incredibly unfair for insurers to be taking this position," she said.
There is disagreement over whether most travellers are due a refund from their travel insurance.
Frances Tuke from the travel association Abta thinks they are not.
"Most travel insurance policies probably won't cover you at this instance for this type of cancellation," she said.
Martin Rothwell of World First Travel Insurance agrees.
He said customers should look to their tour operator instead: "If a traveller chooses to cancel their holiday they are likely not to be covered under most travel insurance policies as this is their own personal disinclination to travel.
"General 'disinclination' isn't covered under any UK travel insurance policy."
However, the Association of British Insurers insists many policies do cover this type of cancellation and people should check their policies carefully.
It said: "In circumstances where you are an independent traveller, our understanding is that most travel insurers will cover for cancellation."
BBC Radio 4's Money Box was broadcast on Saturday 2 May 2009 at 1204 BST