CATHOLIC parishioners are stepping up the fight to ban "sexualised" advertisements from billboards.

Matthew Restall and Bridget Spinks have 4000 signatures, including that of Archbishop of Sydney Cardinal George Pell, and are hoping to collect as many as 100,000 by January, when they will be submitted to the NSW and Victorian parliaments to be tabled.

Mr Restall said he took the action after seeing an advertisement on the side of a vehicle advertising a car wash, showing a scantily clad woman lying in a "suggestive position".

"It was offensive. The aim of the campaign is to remove all forms of sexualised advertisements from billboards and sides of vehicles," he said.

Ms Spinks said there was great support - from both religious and non-religious people - for the campaign, which has been backed by The Catholic Weekly .

"It's not just something that Catholic people are against," Ms Spinks said.

She is hoping to take the campaign statewide.

"Who knows what our children are having to deal with," she said. "By 2040, if no one does something now, the level of our community standards is going to drop."