Online retail giant Amazon is said to be preparing to roll out its grocery service beyond Seattle, the only city the service is offered in at present.

The e-commerce firm has operated its Amazon Fresh service, which delivers dairy, fruit and meat produce, for six years in Seattle. However, the digital retailer now has plans to extend this to California, according to Reuters.

Amazon will start with Los Angeles and San Francisco, and could potentially launch in 20 other urban areas – inside and outside the US – in 2014, sources told the publication.

At present, Amazon does have an online shop offering food and beverages in Germany, which it launched in 2010.

Reuters says that new US warehouses will have refrigerated areas for food, but also space nearby to store up to one million general merchandise products.

It is understood Amazon has opened around 20 new distribution centres since 2010 across the US and operates one of the most sophisticated distribution chains in the world.

Amazon did not return a request for comment.