OCBC, Singapore's third-ranked bank, on Wednesday posted a more-than-feared 13 percent decline in quarterly profit as global market turmoil quadrupled bad debt charges and warned of challenges ahead.

Singapore lenders, which have so far largely dodged the meltdown in credit markets that triggered deep losses for Western banks, now face the rospects of weakening Asian economies and rising bad debt.

"The global financial crisis has carried us into uncharted territory over the past few months and is unprecedented in its scale and impact," OCBC's CEO David Conner said in a statement.

"The next few quarters are expected to be challenging for individuals and businesses around the world."

OCBC earned S$402 million ($272 million) in the three months ended September compared with S$463 million a year earlier, worse than the S$417 million average estimate of four analysts polled by Reuters.