It was a bizarre cat-and-mouse game, played on Sunday across scores of makeshift billboards in New York.

One group of artists and activists spread across Lower Manhattan, transforming innumerous wheat-pasted posters  the ones that readily sprout over scaffolding  into their own canvas.

They would whitewash the posters and then create their own work, or allow anti-advertising advocates to spread their own messages.

But just as quickly as they whitewashed and put up art, workers arrived to put up new posters where the artists had obscured the old ones.