Sainsbury’s is to step up its clothing offer as it prepares to trial selling fashion online.

The supermarket chain will begin the online fashion pilot in August. It is one of the first initiatives from Mike Coupe who takes over from Justin King as chief executive in July.

The grocer is set to announce the move on Wednesday when it will reveal its first quarter update, according to the Financial Times.

Sainbury’s director of non-food trading James Brown said the move was “the next step in our evolution in terms of clothing”.

Sainsbury’s will invite a couple of hundred customers in the Midlands to participate in the trial. More than 80% of the range will be available to order online. If the trial is a success Sainsbury’s will roll it out in 2015.

“We want to test [online] to make sure the customer proposition and journey are right,” said Brown.

Sainsbury’s trades under the Tu fashion brand, competing with Asda’s George brand. It is the UK’s seventh-largest clothing retailer by volume and the 11th in terms of value.

The supermarket will fulfil online orders from its clothing distribution centre in Bedford, which it anticipates will grow.

Sainsbury’s director of online Robbie Feather said: “The platform we are trialling is a scalable platform. If all goes well, we will be able to scale up quite quickly.”

The timing of the trial means that Sainsbury’s will be fulfilling orders for the back-to-school period, Halloween and Christmas, as well as several important fashion launches.

Sainsbury’s already sells homewares online, but Feather said clothing was an important “anchor” for its online business.

Sainsbury’s is expected to post a 1 to 1.5% fall in like-for-likes in its first quarter.