“AMERICAN IDOL” host Ryan Seacrest‘s high-end T-shirt business, R Line, is a fashion flop!

Ryan struck an exclusive deal with Los Angeles-based JEM Sportswear to launch the line last year, but the deal was dissolved after dismal sales, The ENQUIRER has learned.

“When Ryan’s T-shirt collection first came out, everyone thought it would be a huge success,” said a fashion industry insider.

“American Idol” is the most popular show on television, and Ryan wore the shirts night after night in an attempt to create buzz for the brand. Unfortunately, that big buzz translated into a big bust after the T-shirts leaped from small specialty shops to large department stores such as Marshall Field’s and Bloomingdale’s.

“The flashy tees, which Ryan helped design, were monumental flops and sat there like stones,” said the insider. “In the end you couldn’t give them away!”

The line was marketed to young men and boys, but the target audience complained that the shirts were “too gay-looking.”

But specialty stores that cater to a largely homosexual clientele balked at carrying R Line because Ryan — a self-described metrosexual — has consistently denied being gay.

Said the insider: “Ironically, if Ryan were gay and had come out publicly, the shirts probably would have sold like hot cakes!”