The U.N. secretary-general is warning that "Yemen is collapsing before our eyes" and the international community can't stand by and watch.

Ban Ki-moon addressed the U.N. Security Council on Thursday before a briefing by the U.N.'s Yemen envoy, Jamal Benomar.

Alarm has risen after Houthi rebels declared they had taken over the government of the impoverished nation that is home to what is considered the most dangerous branch of the al-Qaida terror network.

Benomar is warning the council that instability in Yemen is creating conditions for al-Qaida's re-emergence.

Speaking from Yemen, Benomar says he is "in the middle of delicate negotiations" daily with parties involved.

He says "Yemen is at a crossroad: Either the country will descend into civil war and disintegration" or a political transition will work.