Outdoor clothing retailer Patagonia has filed a lawsuit against Gap Inc for copying its iconic flap pocket. The American brand said the design has been used on its fleeces for over three decades.

In a filing in a San Francisco federal court, Patagonia claims Gap’s fleece has striking similarities, featuring a similar rectangular logo above the flap, contrast coloured piping along the collar, cuff and waist.

Patagonia said it is not the first time Gap has copied its designs, having previously warned the retailer and alleging “adoption of designs and logos bearing even more similarity cannot have occurred by accident.”

The trademark suit, which was filed on 22 November, comes at a time when Gap has been reducing its inventory, and returned to profit in the last quarter.

According to Reuters, Patagonia first introduced its Snap-T pullover fleece in 1985 and added the flap pocket four years later. The design has been included in exhibitions at New York's Museum of Modern Art and London's Victoria & Albert Museum.

In October Patagonia filed a lawsuit against Walmart for allegedly copying its P-6 Trout logo and artwork on apparel items such as t-shirts.

Image: Patagonia fleece via Patagonia.com