Frozen by shutdown, US warns of 'catastrophic' default

President Barack Obama demanded an end on Thursday to a three-day government shutdown he decried as a reckless "farce," piling pressure on Republicans to climb down first on a budget impasse.

The US Treasury meanwhile warned of "catastrophic" consequences if there is no deal within weeks to raise the country's debt ceiling, and the IMF's chief said navigating a way out of that next crisis was "mission critical."