How to use a supported language by gherkin in Spec

Question

I want to use persian language for authoring BDD scenarios using Specflow in Visual Studio 2013. I added following config to specflow config section:

<language feature="fa-IR" tool="en" />

But when Specflow tries to generate test out of the scenarios, it emits following error:

#error The specified feature file language ('fa-IR') is not supported.