Celebrities including Miranda Kerr and actress Melanie Griffith have been spotted creating the illusion of a skinnier size thanks to a dark panel down the side of the trousers.

Now all British women will get a chance to try out the effect, thanks to a £16 ($25) version on sale at Asda.

The beige Illusion Jeans are designed to slim and elongate legs by drawing the eye down the length of the body.

Asda created the jeans, available in sizes 8 to 24, for its George range after a quarter of women aged 16 to 70 said their legs were their main body hang-up.

Designer Kausar Mitha said: “The panel is slightly wider at the top, around the hip and thigh area, and then tapers down the leg.

“This is because women’s widest point is at the top of thigh. The panel draws the eye in and then follows the contour of the body, which creates an illusion of slimmer legs and hips.

“We tried five different-sized panels and this was the one that made the wearer look most svelte. The jeans are also made from stretch cotton, which gives a more toned look. The vertical panel adds an illusion of extra length.”

Miranda Kerr has been spotted creating the illusion of a skinnier size thanks to a dark panel down the side of the trousers

The trousers are Asda’s latest addition to a line that began with the Illusion dress in April.

The frock, which sold out within a week, was followed by the Illusion swimsuit in May. Next month, the retailer will launch a pair of Illusion jeans in blue with a black stripe on the inside thigh, for those who feel this is their problem area.

Victoria’s Secret model Miranda Kerr was spotted last month in a pair of beige-and-black trousers similar to the Asda jeans, while actress Melanie Griffith was recently pictured in a black-and-white version.

Kate Winslet kicked off the trend for optical-illusion clothing when she wore a white-and-nude dress with black panelling to the premiere of Mildred Pierce at the Venice Film Festival last September. Since then, a host of celebrities – from Kate Moss to actress Liv Tyler – have donned the flattering dresses.

Kausar Mitha said: “We have had lots of customer demands for slimming clothes. Legs are always a focus point that people are not happy with so we wanted to give them a product that made them appear a dress size smaller and gave a smoother silhouette.

“Lots of celebrities have been wearing illusion clothes recently. We wanted to give our customers something similar but affordable.”

George brand director Fiona Lambert said: “Shopping for jeans that look and feel great can be hard for women. George has come to the rescue, using clever design to create something flattering in a staple wardrobe item for every woman.”

However, critics last night labelled the burgeoning market in slimming clothing “dangerous”.

Image consultant Angela Marshall, owner of Appearance Management, said: “There is a lot of pressure to be thin. Even very slim celebrities are wearing clothes designed to make them look even smaller. This sends out a dangerous message.

“The trend for slimming clothes has gone too far. A lot of designers don’t even know how to make clothes for a curvy shape.

“I wish the fashion industry would let people be what they are born with. We need to start celebrating healthy bodies.”