Marks & Spencer's new website has contributed to an 8.1% fall in online sales over the past three months, the retailer reported in its latest trading update.

The retailer said in May that its new £150 million website would take "four to six months" to settle in, after it finished migrating the website from Amazon to its own, in-house platform. The replatforming of the website, completed mid-February, was a major infrastructure project for M&

However, customers have struggled to navigate the new website and have come across issues such as having to re-register for existing accounts, the options for different sizing of clothing being invisible, and not being able to select a new delivery address.

In the company's quarterly results to June 28, Marc Bolland, M&S chief executive, said: "We have seen a continued improvement in clothing, although as anticipated the settling in of the new M& site has had an impact on sales."

The website also had a negative impact on M&S's general merchandise sales, which declined 0.8% in the period.

Despite these figures, M&S insisted that its new web platform was "technically resilient" and that it had received positive customer feedback on the website's "enhanced" fashion and style content.

"As previously indicated, we are now focussed on optimising the website commercially, with updates made on a regular basis. We have recently seen a gradual improvement in sales performance, despite a lower level of promotional activity," the company said.

In a shareholder meeting to discuss the latest results, M&S revealed that just half of the six million users of its old website had registered for the new site, the Guardian reported.

Meanwhile, the company's finance director Alan Stewart likened the clunky website to being "a bit like going to the supermarket for milk, they've moved it and you can't find it immediately".

M&S CIO Darrell Stein, responsible for the replatforming of the new website, left the company for Reckitt Benckiser.