There was once a time when a vegan in McDonald's would have settled for a gherkin between two bits of bread.

But now the fast-food chain is preparing to launch its first vegan burger amid growing appetite for plant-based diets.

McDonald's boss Steve Easterbrook said he is considering bringing in a plant-based burger to help appeal to new customers at a time when its competitors are cashing in on the dietary trend.

McDonalds is considering bringing in a plant-based burger to help appeal to new customers at a time when its competitors are cashing in on the dietary trend (stock photo)

The chain's biggest rival Burger King launched its own vegan Impossible Whopper in April and has since seen an 18 per cent rise in visitor numbers to US branches where the burger is being trialled.

Meanwhile British bakery chain Greggs has enjoyed roaring success after bringing in its vegan sausage roll, helping sales top £1billion for the first time.

McDonald's has been under pressure to broaden its menu options for some time – and though it recently launched a spicy vegetarian wrap, it currently offers no certified vegan meals.

British-born Mr Easterbrook, 52, said its German outlets already offer a vegan burger and he is considering selling it in other countries.

He added: 'We're keeping a close eye on it so watch this space.'