Google plans to extend its online advertising network to offline billboard ads, according to reports of a new patent filing.

The search leader would allow retailers to buy space on local interactive ad hoardings that would display corresponding ads when the advertiser has items in stock.

“Stores buying advertising time on local electronic billboards are able to connect their stock-control computers to the network,” New Scientist reported. “The ads are displayed in rotation, but only until the stock-control computer reports the product as sold out. At that point, the ad is omitted from the cycle until the product is restocked.”

The billboards would be connected to the internet, raising the prospect of Google harnessing its AdWords capabilities to extend its advertising dominance to the real-world display ad sector.