China's politically sensitive trade surplus fell in September for the second straight month, reflecting the ongoing weakness of the global economy.

The government's custom bureau says the country posted a $14.5 billion surplus last month, compared with a $17.8 billion surplus posted in August and a $31.5 billion surplus in July, which was the highest mark in two-and-a-half years.

The bureau says imports were $155.1 billion in September, an increase of 20.9 percent from the same month a year ago, while exports rose 17.1 percent to $169.6 billion. Imports in August rose 30.2 percent, while exports soared 24.5 percent.

Demand for Chinese-made goods has been hurt by falling demand in Europe and the United States.

China's huge surpluses have been a source of friction with its major trading partners, who say Beijing artificially depresses the value of its currency to gain an unfair advantage.

The U.S. Senate passed legislation Tuesday that would punish countries that deliberately undervalue their currencies. Beijing says the bill will cause serious damage to bilateral relations with Washington.