Amazon has been accused of creating a shoe "strikingly similar" to one designed by environmentally-friendly footwear manufacturer Allbirds.
The shoe firm's founders Tim Brown and Joey Zwillinger have written an open letter to Amazon boss Jeff Bezos.
They said Allbirds was "flattered" at the similarities between the products and offered to help make it "match our approach to sustainability".
The BBC has approached Amazon for its reaction.
The shoes which sparked the row are Allbirds' wool runners, which are made from New Zealand merino wool.
Amazon's 206 Collective wool blend sneakers, for sale on its US website, are about half the price and made from a mixture of wool, polyester, nylon and viscose.