HONG KONG — China, one of the United States’s biggest creditors, urged American policy makers on Thursday to act to protect investors’ interests, highlighting rising concerns around the globe about the protracted budget talks taking place in Washington.

Officials in Washington are locked in tense negotiations over the government debt limit, which the Obama administration says must be raised from its current level of $14.29 trillion to allow the government to pay its daily bills and service any debt coming due.

Any failure to pay due debt would effectively amount to a default, which, however briefly, could shake confidence in the American economy and unsettle global financial markets.

Late Wednesday, Moody’s Investors Service sharpened attention on such an outcome by warning that it might cut its top rating for the United States. Moody’s cited a “rising possibility” that no deal would be reached before the United States government’s borrowing authority hits its limit on Aug. 2.