It is a fraud many people would scoff at the idea of falling for – buying a fake handbag or perfume online through what appears to be a genuine website. For others less worried about the legal, moral or quality implications, it is a way to buy a designer item without the price tag.

The sale of fake goods online has blossomed, as have the problems that come with the illegal products – from perfumes made partially with urine to phone chargers that combust in the middle of the night and children’s toys with dangerous levels of lead. New figures show that British police have shut down 31,000 sites this year in an attempt to stop the spread of counterfeit goods as part of an international effort to make shopping on the internet safer.

Telling the good from the bad online has long been a problem. With Christmas around the corner, here is how to avoid getting stung by unscrupulous sellers:

How big is the problem?

Online piracy and the sale of counterfeit items is a large industry and growing, it would appear. Counterfeit bags and watches have long been a feature on every beachfront where holidaymakers have taken their summer break, but with the growth of the internet has come a surge in sales of fake goods made by workers in dismal working conditions and an increasing number of people prepared to buy them.

As a result, a coalition of police forces was assembled in 2014 with the aim of making the internet a safer place for people to shop, under Europol, the EU’s agency for police cooperation. The latest figures, released last week, show the group of police forces shut down 33,600 domain names from December last year to the middle of last month. Of these, the majority (31,000) were in the UK following action by the City of London police’s intellectual property crime unit.

The vast majority of these sites, while having a .uk domain name, originate from criminal gangs in Asia that set them up using the details of often unwitting members of the UK public, said DI Nick Court, from the City of London police.

In some cases, people who have had their identity stolen could be associated with hundreds of sites and have received complaints about the goods sold to other consumers. Almost half of the sites are for clothes and the majority of the rest are for footwear. The remainder deal in bags, jewellery, perfume and other consumer goods. Many large fashion brands have their own inhouse antifraud teams set up to tackle fakes and forward details to the police.

How do you know it’s fake?

The old adage remains: if it looks too good to be true, it probably is. Court says it is highly unlikely that a pair of trainers which retail for £100 on the high street would be available for £25 online.

Adam French, from the consumer group Which?, said people should look at whether there is branding attached and if the packaging is of low quality. Whether you know of the website that it is coming from also adds to credibility, or lack thereof.

“All of those things can start to combine to create a picture of a legit product,” he said.

“Anything that is particularly trending and popular at that point of time and is a ridiculous price point, I would say to be extremely sceptical of.”

Is it that big a deal?

There are two types of people who buy fake goods – those who don’t know and those who don’t care. Much like buying a cheap handbag or watch on holidays, many people don’t see a problem with getting what appears to be a designer item for a fraction of the price found in designer stores. It is these people who are urged to consider their actions, particularly the background of where their purchase comes from.

“They come with a lot of strings attached and a lot of them are around safety,” said French. Earlier this month, a consignment of “Princess Catherine” dolls was stopped in the Czech Republic after being found to have a high level of a toxic compound which is suspected of causing cancer. Research by Which? earlier this year found that some slime toys for children contain unsafe levels of boron, which can cause vomiting and impair fertility. In 2015, a fake NutriBullet blender exploded in safety tests after just four seconds.

“To the people who are taking a chance, they need to seriously think twice about the danger that the product poses for themselves and their family,” said French.

Court said consumers in the UK are increasingly concerned about where and how the products they use are produced, whereas counterfeit goods will inevitably be made by workers who may have been trafficked and under very poor conditions. Handing over personal details also leaves people open to identity theft from the criminal gangs that operate the sites and whose only goal is to make money. That money is then used to fund other types of organised crime.

What to do if you find a fake?

There are a number of avenues if you have been sold fake goods, Which? says. Action Fraud, the national cybercrime reporting centre, has an online reporting tool and also suggests contacting your local Trading Standards office. On eBay, Which? recommends reporting items to the seller first. If the issue is not resolved, a dispute can be raised via eBay’s buyer protection process.

Citizens Advice says buyers are entitled to a full refund on fake goods within 30 days of paying for them. Over that period but less than six months later, the seller can give a real version of the item to replace the fake one. In some cases, sellers will claim it was obvious that the goods were fake as they were so cheap and try to use this is a reason not to give money back. Citizens Advice says in this case, sellers would be breaking the law and your legal rights remain.