Belgian Cycling Federation -- We're ASHAMED of Our Drunken Athlete

Belgian cyclist Gijs Van Hoecke didn't just stain the crotchel region of his pants during a drunken post-event nightclub bender in London ... he stained the good reputation of the Belgian Cycling Federation ... so says the org.

We posted the photos ... showing a completely wrecked Van Hoecke being carried out of a British nightclub earlier this week ... barely able stand or keep his eyes open.

We reached out to the BCF for comment ... and a rep told us, "I can let you know that the Belgian Cycling Federation regrets the conduct of [Gijs Van Hoecke] after the competitions."

In fact, the Belgian Olympic Committee reportedly put GVH on a plane and flew him home after the pics came out.

According to reports, the cyclist told his home paper, "I made a big mistake. I'm happy my parents didn't tell me off. They understand that I needed this" ... but since we don't speak Dutch, TMZ can't confirm the accuracy of the translation.