China’s vast foreign exchange reserves showed on Friday their first quarterly drop since 1998. The decline was partly attributed to a slowing Chinese economy and capital outflows amid worldwide economic ambiguity.

Reserves fell by $20.5bn to $3.18trn in the final quarter of 2011, said the People’s Bank of China.Net quarterly decreases are rare for China, which is momentarily the largest holder of foreign exchange reserves globally.

On a year-on-year basis, however, the country’s fx reserves still expanded from its previous $2.85trn at the end of 2010, the bank said.