Here's the deal ... the singer is one of the newest faces for the famed fashion line, and one of the shots that was released as part of her campaign has actually gotten censored in the UK -- all thanks to a government agency known as the Advertising Standards Authority (ASA).

According to them, this specific ad featuring FKA violates one of its provisions in that it could "present her as a stereotypical sexual object" ... this because the pic places "viewers' focus on the model's body rather than on the clothing being advertised." They go on to say that this image is likely to cause serious offense ... so they're completely yanking it in public.

The photo in question shows Twigs butt naked -- but covered up with a denim shirt of some kind, which is draped over her ... and some side-boob showing, as well as some butt/thigh.

It's not the raciest shot in the world, and yet ... it seems to have been too much for the Brits. FKA came out and slammed the decision, saying she sees herself as a strong woman of color in this photo -- while going on to suggest there are double standards at play here.

She might have a point ... there's another recent Calvin Klein ad with Kendall Jenner -- where she too is somewhat topless -- that's been running in the UK without issue.

Of course, there's also the Jeremy Allen White campaign that dropped last week -- and we're sure that's getting a ton of play across the pond. Unclear if FKA thinks this enforcement on her pertains to race, sex or both ... but in any case, she feels she's getting a raw deal.

She writes, "i am proud of my physicality and hold the art i create with my vessel to the standards of women like josephine baker, eartha kitt and grace jones who broke down barriers of what it looks like to be empowered and harness a unique embodied sensuality."