China's trade contracted in March by an expectedly wide margin, adding to signs of weakness in the world's second-largest economy.

Customs data on Monday showed exports fell 15 percent compared with a year earlier to $144.6 billion following a 20.5 percent contraction the previous month. Imports declined 12.7 percent to $141.5 billion.

Unexpectedly weak Chinese import demand could fuel fears that first-quarter economic growth, due to be reported this week, might have fallen further after hitting 7.3 percent in the final quarter of 2015.

Economist Brian Jackson of IHS Global Insight says the "dismal performance" on trade increases the chances Beijing might roll out more help for Chinese exporters following the announcement of export rebates in March.