Deepening fears for the health of the global economy pushed world stocks to three-week lows on Friday after China exports contracted by a fifth, sending shares in some of the country's key indexes more than 4 percent lower.

The February data out of Beijing came in well below expectations of a 4.8 percent drop and worsened the already brittle mood on world markets, after European Central Bank slashed growth forecasts and unveiled a new round of policy stimulus on Thursday.

While the timing of the Lunar New Year made it difficult to draw a true signal from the China data noise, the scale of the drop was alarming, especially when coupled with somber new data from Germany and Norway.