Martin Lewis has issued a warning to customers ahead of Amazon Prime Day.

Confusingly, the two-day event begins from one minute past midnight on Tuesday, July 16 and runs until the end of Wednesday.

The sale has become famous for offering deep discounts on all sorts of items from air fryers to headphones, games, fitness kits and of course, Amazon techs like Kindles, Echos and Ring doorbells.

There are laws in the UK that state a product must be listed at a given price for at least 28 days in 6 months before it can be sold at an advertised lower sale price for five months. This is to stop retailers from increasing the price for a day or two and then instantly cutting it for a ‘sale’.

How long have Amazon’s products been at full price for, and have they been cheaper before the sale?

While Amazon does offer plenty of genuine deals, there is a way to weed out the good deals from the less attractive ones. Martin Lewis’ MSE has advised people about a website called CamelCamelCamel.

This is a site which tracks Amazon's price history for any given item.

MSE said: “As an example, we found a Breville Barista coffee machine "38pc off" at £350 - but it was £301 in February this year.”

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So this site can tell you what’s a real deal and what’s more expensive in the Prime Day sale than it was before.

Finally, don’t get caught out by changes to minimum delivery prices. In June, Amazon upped the threshold for free delivery from £25 to £35 for non-Prime members.

There are ways around it though, such as adding a very cheap item (some start at 22p) to your basket to get over the £35 threshold, saving £3 to £5 on delivery, or signing up for a free trial of Prime and then cancelling it before it renews.