Oscar de la Renta has tough words for Michelle Obama

[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2009/images/04/03/art.michelle.gi.jpg caption=" Oscar de la Renta thinks Michelle Obama should not have worn a sweater to Buckingham Palace."](CNN) - Michelle Obama's fashion choices at the G20 summit have drawn widespread praise, but at least one famous designer thinks the fist lady made a major faux pas in her wardrobe choice for a private audience with Queen Elizabeth II.

"You don't...go to Buckingham Palace in a sweater," Oscar de la Renta told Woman's Wear Daily regarding Mrs. Obama's decision to wear a cardigan over an Isabel Toledo-designed dress for the private meeting.

De la Renta also said the first lady - who often sports relatively affordable American brands - should broaden her wardrobe and seize an opportunity to spur the flailing fashion industry.

“American fashion right now is struggling,” he said. “I think I understand what [Obama and her advisers] are doing, but I don’t think that is the right message at this particular point."

"I don’t object to the fact that Mrs. Obama is wearing J. Crew to whatever because the diversity of America is what makes this country great. But there are a lot of great designers out there. I think it’s wrong to go in one direction only," he added.

But J. Crew is likely hoping the first lady doesn't change her style any time soon. When Mrs. Obama was photographed wearing a $300 J. Crew "crystal constellation" cardigan from the mid-market retailer Tuesday, the item sold out on the company's Web site only hours later.

A spokesman for J. Crew said the item has also  sold out in nearly all the company’s stores as well.