file_get_contents not working for fetching data from facebook using batch requests

Question

file_get_contents not working for fetching fata from facebook using batch requests.Am using the code below:

  $url='https://graph.facebook.com/?batch=[{ "method": "POST", "relative_url":"method/fql.query?query=SELECT+first_name+from+user+where+uid=12345678"}]&  access_token=xxxxxxx&method=post';
 echo  $post = file_get_contents($url,true);
it produces 
    Warning: file_get_contents(graph.facebook.com/?batch=[{ "method": "POST", "relative_url": "method/fql.query?query=SELECT+first_name+from+user+where+uid=12345"}]&access_to‌ ​ken=xxxx&method=post): failed to open stream: HTTP request failed! HTTP/1.1 400 Bad Request in /home/user/workspace/fslo/test.php on line 9