China's exports and imports contracted again in May in a sign of weak global and domestic demand.

Customs data released Wednesday showed exports fell 4.1 percent from a year earlier, compared with April's 1.8 percent contraction. Imports contracted 0.4 percent, an improvement over April's 10.9 percent contraction.

Trade weakness could complicate Beijing's efforts to pull the world's second-largest economy out of a slump. Weak exports could require more economic stimulus, setting back efforts to reduce reliance on trade and investment to drive growth.