The online fashion giant Asos has warned that trading was "significantly behind expectations" in November.

While the British company says that sales growth has continued, it has revised it previous growth estimate of 20-25% down to 15%. 

It's the latest major retailer to warn of difficult trading conditions in the run-up to Christmas.

In an unscheduled profit warning published on its website, Asos said that "conditions remain challenging".

The company says: "Whilst trading in September and October was broadly in line with our expectations, November, a very material month for us from both a sales and cash margin perspective, was significantly behind expectations.

"The current backdrop of economic uncertainty across many of our major markets together with a weakening in consumer confidence has led to the weakest growth in online clothing sales in recent years. We have recalibrated our expectations for the current year accordingly."

It highlights a "high level of discounting and promotional activity" across the clothing market, in the wake of Black Friday and other promotions that have become increasingly prevalent in November.

Asos said it has also increased its own promotional activity, leading to higher discounting on products.

Nick Beighton, Asos CEO, explained: "We achieved 14% sales growth in a difficult market, but in the light of a significant downturn in November, we think it's prudent to recalibrate our expectations for the full year.

"We are taking all appropriate actions and our ambitions for ASOS have not changed".