You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allpages gapcontinue="Komoe_Basin" />
  </query-continue>
  <query>
    <pages>
      <page pageid="2075" ns="0" title="Kagera Basin">
        <flagged stable_revid="7949" level="0" level_text="stable" />
      </page>
      <page pageid="1887" ns="0" title="Kaladan Basin">
        <flagged stable_revid="7698" level="0" level_text="stable" />
      </page>
      <page pageid="2043" ns="0" title="Karnaphuli Basin">
        <flagged stable_revid="7857" level="0" level_text="stable" />
      </page>
      <page pageid="1095" ns="0" title="Kazakhstan">
        <flagged stable_revid="6246" level="0" level_text="stable" />
      </page>
      <page pageid="1821" ns="0" title="Kemi Basin">
        <flagged stable_revid="7623" level="0" level_text="stable" />
      </page>
      <page pageid="1751" ns="0" title="Kenya">
        <flagged stable_revid="7537" level="0" level_text="stable" />
      </page>
      <page pageid="1732" ns="0" title="Kingdom of Cambodia">
        <flagged stable_revid="7518" level="0" level_text="stable" />
      </page>
      <page pageid="1907" ns="0" title="Klaralven Basin">
        <flagged stable_revid="7718" level="0" level_text="stable" />
      </page>
      <page pageid="1786" ns="0" title="Kogilnik Basin">
        <flagged stable_revid="7573" level="0" level_text="stable" />
      </page>
      <page pageid="2176" ns="0" title="Komati Basin Water Authority (KOBWA)">
        <flagged stable_revid="8157" level="0" level_text="stable" />
      </page>
    </pages>
  </query>
</api>