Route conflict with public folder in Laravel 4.1.31

Question

I have a route in my app/routes.php i.e.

Route::get('sitemap', [
  'as' => 'sitemap', 
  'uses' => 'PageController@sitemap'
]);

And sitemap.xml in public/ folder.

When I hit the URL http://example.com/sitemap it returns the content written in public/sitemap.xml rather than executing a specified route from app/routes.php Although, http://example.com/index.php/sitemap works fine.

I need the standard solution for this.