London, Jan 11 (Agencies): British fashion houses are reportedly poring over every cut, hem and button of the clothes of royal bride Kate Middleton, knowing shoppers are desperate to recreate her elegant style. But they may be sued by the royal family if her name is used for selling merchandise.

When it comes to fashion, everything Kate Middleton wears benefits a huge boost in sales and copycat designs.

But using the "Kate Middleton brand" to sell replica dresses could now lead to retailers being sued for thousands of pounds, royal aides and industry experts have warned.

Kate will wed Prince William April 29.

Though there are no written rules, officials said firms would be warned that they risk falling into trademark and copyright law if they use her full name on merchandise, according to the Daily Mail.

But if designers want to cash in by copying her outfits and adding an explicit "Kate Middleton" label, they could face the wrath of the royals.

"Her name is now controlled by the royal family. She has a reputation to uphold and because of that she is, to all intents and purposes, akin to a brand or marque," an official said.

While William and his fiancee agreed to relax rules on the use of official pictures for wedding memorabilia, the royal household has made clear it could enforce rules on the use of Kate's name in association with non-wedding paraphernalia.

"It is highly unlikely that we would have any objection if a company wanted to call a dress 'the Kate dress'. 'Kate' isn't specific to Catherine Middleton. It may, however, be a different scenario if it was called the "Catherine or Kate Middleton" dress as that impacts on personal copyright. Or indeed if a company was suggesting a dress was officially endorsed by Catherine," another official said.

Leading trademark lawyer Eric Ramage said: "If Kate Middleton could prove that the purchasing public assumed she had endorsed the dress... the firm could pay costs and damages in the region of tens of thousands of pounds in court."

A 399-pound royal blue dress she wore to announce her engagement sold out within a day. Replica versions of the 159-pound white gown she chose for the engagement portraits were put up for sale on eBay for 370 pounds the next day.