PRECIOUS-Gold slips to 1-week low as investors' confidence wanes

LONDON, Jan 24- Gold fell to a one-week low on Thursday after a repeated failure to break above a key chart level hurt investors' confidence in the metal, and as U.S. policymakers postponed talks on extending the U.S. debt ceiling. Spot gold slipped to a low of $1,675.04 and was down 0.4 percent at $1,677.99 an ounce at 1118 GMT.