ASOS customers were alarmed on Tuesday morning after a push notification claimed the fashion retailer’s data system had been hacked.

The message appeared through the ASOS app. It read: Dear ASOS DPO and IT, we have fully compromised the Snowflake instance. Engage with us, or we will leak it.

The claim is unverified. ASOS has not confirmed that it suffered a breach. It has not said that any customer information was accessed. The company has also not explained what the sender meant by a Snowflake instance.

Snowflake is a US cloud-based company whose platform stores and processes data for thousands of businesses. There is no evidence that Snowflake’s wider platform has been compromised.

Experts note that Snowflake itself usually calls each customer’s setup an account rather than an instance. The strange wording adds to the doubts about the message’s authenticity.

Customers should be cautious of follow-up messages claiming to be from the retailer and should not click unknown links.