An advertisement hoarding featuring a bikini-clad Beyonce Knowles has been branded 'obscene' by angry Las Vegas residents.The R&B singer appears on a massive advertising hoarding for the city's local radio station, but residents of the Sin City are petitioning to have the raunchy image taken down."It's obscene. I have my two little grandkids coming over here, and they don't need to be seeing that," The Sun quoted a resident, as saying."You can change the channel on the TV but you can't change that," the resident added.However, the billboard has received the backing of city officials."The billboards were taken from publicity shots and this is the way those people perform," the station manger said."So, to show them in a jogging suit probably wouldn't be the right thing."It complies with all the locational criteria that are set out in our code of conduct," the manager added.