An antibillboard group has sued Philadelphia alleging the city entered illegally into a sweetheart agreement with four billboard companies in 2006.

SCRUB, which fights outdoor advertising, alleged in the suit filed on Tuesday that the agreement eliminated fines and lowered fees for the companies, and legalized hundreds of unpermitted signs in the city.

The city agreement, with CBS Outdoor, Steen, Clear Channel and Keystone, takes away legal rights from residents and community groups who want to get rid of billboards, the suit says.

The suit seeks to void the agreement and require that billboard companies comply with existing regulations.

The named plaintiffs in the suit are Lynn McConville of the 4700 block of Kingsessing Avenue, and Dea McAlonan, a Lansdale resident who co-owns commercial property in the city.