The Trading Standards Institute is advising travellers to report travel agents who charge more than the brochure price for holidays after a survey revealed many were doing so illegally.

The survey was conducted by 27 local authority Trading Standards bodies in England and Scotland. It revealed that the same package could vary by up to £1,260 between agents, suggesting they were illegally basing their prices on supply and demand.

The TSI said it was technically against the law for agents to charge amounts that were different to the latest price printed in a tour operator brochure and that hiking prices could end in legal action, although last-minute discounts on holidays were acceptable.

The survey was sparked by a pilot study conducted in Durham which found that a one-week, half-board family holiday to Tenerife for a particular week cost £1,228 with one travel agent and £2,488 with another.

In Barnet, north London, one holiday to Turkey was quoted at £3,032 in a brochure, but trading standards officers found it could not be bought through a travel agent for less than £3,628; one agent costed it at £4,032.

Although the TSI would not name specific travel agents, it said a mixture of individual companies and national chains were at fault.

It is contrary to the Consumer Protection Act to publish inaccurate prices, whether they are higher or lower than those charged, although the TSI conceded that the public would be unlikely to report travel agents who were charging less for a holiday than the advertised cost.

'We wouldn't take action over discounted prices because we'd be laughed out of court,' said the TSI's lead officer for the travel industry, Bruce Treloar.

The TSI has asked the public to report any discrepancies in price to their local TS authority so it can collate evidence that shows travel agents are causing detriment to consumers. It would then use this to prosecute agents through magistrates courts at a regional level, or take it to the Office of Fair Trading which could prosecute on a national scale.

A spokesman for the Association of British Travel Agents was quick to refute claims that agents were misleading the public: 'It's like buying a television: prices vary depending where you go. Some agents get better deals than others with tour operators.'

Tour operators are permitted to raise prices legally only when there is an increase in government tax, or when there are changes in exchange rate or fuel prices, but it is very rare for them to do so and the tour operator must absorb two per cent of the extra costs itself.

Treloar said: 'Our advice to anyone planning to book a holiday is to shop around - and view brochure prices with healthy scepticism.'

To report pricing discrepancies, contact your TS authority through your local council. See www.tradingstandards.gov.uk