The advertising industry watchdog has labelled a controversial guerilla tourism campaign in the Northern Territory that isn't shy about going Down Under as obscene.

The Advertising Standards Board has upheld a complaint against a range of merchandise bearing the 'CU in the NT' slogan which argues it is "extremely denigrating to women".

"It is also promoting the acceptance of a highly derogatory term used instead of vagina and is offensive to women in general," the complaint to the ABS read.

The unofficial logo, which makers claim is designed to market the Territory to younger travellers, rippled across social media last November and generated international coverage.

T-shirts, singlets and bumper stickers that share a strong resemblance to official Tourism NT designs are also sold online.

The ASB agreed with the complaint's argument that the promotional material was "not funny or witty."

"The community considered the 'c-word' to be obscene and not appropriate in advertising in any form," the ASB said.

NT Official, the company behind the slogan, claims it's no different to acronyms such as "WTF" and "LMFAO" which the ASB doesn't deem to be offensive language.

It said any adverse findings would "impose an overly strict moral view on a fine tradition of Australian humour and in particular the great tradition of the Aussie larrikin."

"Neither our social media posts nor our products make any reference or distinction along gender lines and do not advocate anything other than an appreciation of the natural beauty of the Northern Territory," NT Official said in a statement to the ASB.

Despite the ruling, the industry body has no powers of enforcement.