San Francisco,  A restaurant group in the US has sued Google for directing customers to unauthorised Google-branded food ordering web pages rather than sending them to the restaurant's own website.

The Florida-based restaurant group called Left Field Holdings, that runs Lime Fresh Mexican Grill franchises, alleged in the lawsuit that Google employs "bait-and-switch" tactics by placing its "Order Online" button at the top of restaurants' profile panels on the search engine, reports Ars Technica.

The large blue button redirects users to a food.google.com page where they can select items from a restaurant's menu and then place an order through a variety of food delivery companies like GrubHub, DoorDash, or Seamless -- and not through the restaurant itself.

These services take a commission from participating restaurants -- as high as 15 to 30 per cent in many cases.

"Google never bothered to obtain permission from the restaurants to sell their products online," the lawsuit read.

"Google purposefully designed its websites to appear to the user to be offered, sponsored, and approved by the restaurant, when they are not -- a tactic, no doubt, employed by Google to increase orders and clicks."

In a statement to Ars Technica, Google said late on Monday it would defend against the lawsuit.

"Our goal is to connect customers with restaurants they want to order food from and make it easier for them to do it through the 'Order Online' button," a company spokesperson was quoted as saying.

"We do not receive any compensation for orders or integrations with this feature," the company added.

When users click the "Order Online" button, they're directed to a page that contains links to food delivery companies, complete with their logos.

"The restaurant's own site gets a link as well, though it's a small, generic 'website' button. In some cases, Google provides an interface for assembling an order, complete with prices and descriptions of the menu items," according to the report.

"Google's 'Order Online' button leads to an unauthorised online storefront -- one owned and controlled by Google -- wherein consumers can place orders for the restaurant's products, all under the restaurant's trade name," the lawsuit read.