The group, which carried out a mystery shopping exercise, found that the holiday insurance sold by travel agents was often more expensive than that sold by banks and insurers. A worldwide single trip travel insurance policy for a family of four costs about £200 more if bought from a travel agent compared with the best buys available across the market.

Travel agents also failed to follow basic procedures to make sure the cover is suitable. Most of the agents visited didn’t explain what the policies covered or asked about pre-existing medical conditions, which if undisclosed can be used to invalidate a policy. None pointed out what was excluded.

This made it more likely people could be sold an unsuitable policy that may not provide them with adequate cover. And holidaymakers left high and dry are completely unprotected.

The Financial Services Authority (FSA) regulates travel insurance sold by banks and insurers. People sold an unsuitable policy can go to the Financial Ombudsman Service for help. But travel agents are excluded.

"Buying holiday insurance from a travel agent may seem the easy option, but you’ll pay more and you don’t have the same protection if you’re sold an unsuitable policy," said Neil Fowler at Which?. "There’s no reason why travel agents should be excluded from insurance regulation. People should have the same protection and peace of mind on holiday regardless of where they’ve bought their travel insurance."

Which? wants the government to include travel agents when it reviews the regulation of holiday insurance next year.

It also urged the FSA to get tougher with those banks and insurers who were not selling the insurance properly.

Although it found that banks and insurers were generally better at selling cover it said there was still room for improvement.

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