America's biggest creditor China asked Washington to handle its debt issue responsibly . It also warned that any large fluctuations and uncertainties” would undermine the stability of global financial system and hinder economic recovery. China has signaled deep unhappiness over this week's deal to raise the U.S. debt ceiling and the way it was accomplished.A Chinese credit rating agency downgraded U.S. debt, saying the deal does nothing to address the underlying problem. Dagong credit rating agency said it was downgrading U.S. debt from A-plus to A because the deal does nothing to improve the United States' ability to repay its debts.The official Xinhua news agency dismissed the negotiating process that produced the deal as a madcap farce of brinksmanship. It said the United States has a runaway debt addiction which has tarnished its credibility and remains as a ticking time bomb. Meanwhile US debt has shot up USD 238 billion to reach 100 per cent of gross domestic project after the government's debt ceiling was lifted. Treasury figures showed, immediately after President Barack Obama signed into law an increase in the debt ceiling as the country's spending commitments reached a breaking point and it threatened to default on its debt.