Travel firms have been forced to defend themselves against accusations that holiday prices continue to fall after special discount periods end.

Kuoni, Virgin Holidays, Sandals, Expedia, Inghams and lastminute.com were named in an investigation by Which? Travel.

The consumer group tracked time-limited deals in July and August 2017.

The promoted offers were found to be available for the same price or cheaper after the deal had ended in half of cases.

Which? has reported its findings to trading standards and the Advertising Standards Authority to investigate whether the companies have broken the law or advertising codes.

The consumer watchdog warned that the firms could be in breach of the Consumer Protection from Unfair Trading Regulations (CPRs) if a retailer’s actions can be shown to be misleading and likely to cause the average person to rush into a buying decision they would not otherwise have taken.

The time-limited promotions – advertised in national newspapers and circulated by email – promised bargain prices if bookings are made before a cut-off date.

But when Which? Travel tracked the deals over three weeks last summer, it found that in 16 out of 30 cases the price was the same – or even cheaper – after the sale had ended.

Many of the ads urged travellers to ‘hurry, book now’ and use online tactics, such as ticking countdown clocks, to create a sense of panic in the buyer, according to the consumer body.

Sandals was offering a seven-night all-inclusive break to Jamaica for £1,465 per person in its Summer Mega Sale. ‘Save up to 60%… Hurry! Only one day left,’ the strapline read.

However the day after the ‘sale’ ended, the price dropped by £50 per person – and continued to run for another week.

The travel company seemingly runs 60%-off promotions back-to-back under various guises, adding another seven days to the countdown clock.

A spokesperson for Unique Caribbean Holidays, the UK operator for Sandals, told Which? it does not intentionally pressure sell or create false book-by dates, and that all its packages are fairly promoted to the customer.

The company added: “We clearly state our sale terms and conditions on our website, which do not breach any advertising guidelines, and in turn do not mislead our customers.”

A Virgin ‘Holiday Sale’ promoted seven nights at Florida’s Coco Key Hotel from £792 per person if booked by 17 August. ‘Won’t last forever,’ the banner read.

On 18 August – a day after the sale had ended – the same package on the same dates had dropped to £677 per person – a £230 saving for two people sharing.

A week later the package crept up to £682 per person, but was still considerably cheaper than the ‘sale’ price.

A Virgin Holidays’ spokesperson told Which? that it would never intentionally advertise anything misleading.

It added: “We are always looking to secure the best possible value for our customers – and should we be able to obtain better offers from our suppliers, these savings will be passed on to benefit the customer.”

Other questionable deals highlighted by Which? included a lastminute.com stay at a Paris hotel with flights.

The day after the promotion ended, the price dropped from £139 to £126 – and this lower rate was still available a week later. Other deals saw prices yo-yo.

Two-nights at another Paris hotel was £404 in Expedia’s ‘flash sale’. After the promotion ended, the break went up to £628 – only to drop again a fortnight later when a new 40% off promotion ran. This time the same stay was available for £382 – £22 cheaper than the original ‘sale’ price.

Which? found that Inghams Italy offered discounted trips to Capri, Milan and Puglia until 4 August. But the expiry date was pushed back twice, meaning the same prices were still being advertised a month later.

A Kuoni ‘special offer’ also continued to run after the deadline, meaning an all-inclusive holiday to Jamaica dropped by £200 per person the day after its initial sale ended.

Kuoni and Inghams said they have reviewed how they promote offers as a result of the findings.