Generating xml within twig template

I am trying to generate a sitemap, which works just fine if I do it in a standard xml file. The problem I am facing is that I need to generate a xml sitemap within twig file.

So i have this file: sitemap.xml.twig with this content:

{{ <?xml version="1.0" encoding="UTF-8"?> }}

{{ <urlset xmlns="http://ift.tt/xwbjRF"> }}
    {{ <url> }}
        {{ <loc>http://ift.tt/14SeN26; }}
        {{ <lastmod>2005-01-01</lastmod> }}
        {{ <changefreq>monthly</changefreq> }}
        {{ <priority>0.8</priority> }}
    {{ </url> }}
{{ </urlset> }}

But I get an error: "message":"Unexpected token

how can i make xml go into twig...? sorry I am new to twig