Tesco is to become the first supermarket to sell clothes on the internet, a move expected to send shockwaves through the UK fashion industry.

The store giant will sell 300 lines of women's clothing online, including its budget fashion ranges Florence & Fred and Cherokee.

Retail experts said the move, planned for launch in late October, was bound to worry other fashion brands in the all-important weeks before Christmas.

It is the latest bid by supermarkets to muscle in on the lucrative clothing market, and throws down the gauntlet to rival grocers Asda and Sainsbury's, who both have their own value ranges.

Asda has already announced plans to launch a similar service next year.

Tesco said it would combine the new move with the relaunch of its fashion website clothingattesco.com, which is currently used to showcase its clothes, but not sell them.

Customers will be linked to Tesco Direct's main grocery website if they want to purchase clothing.

Sean Murray, Tesco head of marketing for clothing, said the move was in direct response to customer demand.

He said: "Not all our customers have access to our clothing ranges in their local stores and many of them have told us how much they would like to be able to buy Tesco clothing online.

"Building on last year's trial, this autumn the best of our clothing ranges will be available through Tesco Direct. By selling online we will be able to reach a greater number of customers eager to buy items from our collections."

A source close to Tesco said the potential for online clothing sales was "substantial" if it mirrored the booming sales in its supermarkets and non-food Homeplus stores.

Professor Leigh Sparks, professor in retail studies at Stirling University, warned that the move appeared to be timed to have maximum impact on the competition.

He said: "The timing is interesting. Internet sales get to a peak at Christmas and that is continually rising.

"Customers also have the concern of if I order before Christmas will it arrive?' but I can imagine they Tesco will have customers who have confidence in them. Tesco have good experience of delivering under pressure."

He added that Tesco was unlikely to draw shoppers from "high fashion" outlets, because it's clothing range was not in the same league.

Fiona Moriarty, director of the Scottish Retail Consortium, said it was a sign that the UK's retail trade was flourishing - and was good news for consumers.

She said: "Retailing is one of the most dynamic industries in the UK. Retailers understand customers. This will undoubtedly be in response to pressure from customers who are increasingly time poor and looking for new ways to access goods quickly and easily."

Contrary to the view of other retail experts, she said it shouldn't cause concern among fashion outlets because they were already ahead on internet sales.

She said: "The main high street retailers for clothing and accessories already have an online presence."

That view seemed to be reflected at fashion chain Top Shop. A spokeswoman said it was not policy to comment on other brands, or to reveal its own sale figures, but she added: "Our online side is very very successful."