Asos has sent an email to customers detailing changes to its returns policy, including threatening to investigate and “take action” if it notices “unusual patterns”.

The email sent this week by the online fashion giant said that customers suspected of ordering, wearing and then returning items in bulk could be at risk of having their accounts suspended.

The email said: “If we notice an unusual pattern of returns activity that doesn’t sit right: e.g. we suspect someone is actually wearing their purchases and then returning them or ordering and returning loads, then we might have to deactivate the account and any associated accounts.”

Asos said the change in its returns policy was driven by the “need to make sure our returns remain sustainable for us and for the environment, so if we notice an unusual pattern, we might investigate and take action”.

The etailer added that the initiative was “unlikely to affect” the majority of its customers and that shoppers who are impacted and believe the retailer has “made a mistake” could speak to its customer care team.

The online retailer is also changing the terms of its returns, offering shoppers who send back items within 28 days a standard refund and those who return after that and up to 45 days an Asos voucher for the amount spent.

The fashion etailer, which stocks more than 850 brands and operates in 200 countries, reported an uplift in quarterly sales driven by its UK performance in March.