XML : How to parse & in XML

I have a problem with the tag & when I want to create a xml. How to resolve the problem ?

Thank

ex

  $page_manager_array[$QpageManager->valueInt('pages_id')]['loc'] = OSCOM::link('index.php', 'PageManager&pages_id=' . $QpageManager->valueInt('pages_id'), 'SSL', false);