8216;US playing with fire on debt limit8217;

8220;To be blunt,to have a debt default in the United States would not only be a financial calamity but should be an embarrassment for every American8221; he said.

Unless the 14.3 trillion debt ceiling is raised by Tuesday,the United States will lose its ability to borrow and start to run out of cash to pay its bills.

Efforts to avoid an unprecedented debt default suffered a new blow on Thursday when some fiscally hardline Republicans blocked a budget deficit plan proposed by their own congressional leaders.

On Friday,President Barack Obama said he was ready to work with top Democrats and Republicans through the weekend to get a debt ceiling accord.

Zoellick said the political standoff in Washington was coming at a time when Europe faced fiscal difficulties and Japan was struggling with low growth and is trying to recover from an earthquake.

8220;So you have an environment that8217;s already fragile and uncertain,8221; he said.