World stocks were set for a third straight week of losses on Friday and commodity currencies took another drubbing as oil prices fell back below $30, keeping alive concerns about global growth, according to Reuters.

European stocks fell more than 1 percent, heading back towards Thursday's 13-month lows, while Asian shares skidded to 3-1/2 year lows.

Oil prices, which posted their first significant gains for 2016 on Thursday, came under fresh selling pressure.

Brent crude fell 3 percent to $29.86, heading for a weekly loss of more than 10 percent. U.S. crude fared even worse, sliding almost 5 percent to $29.75, and was set for a weekly decline of 10 percent.

The collapse in oil prices has spooked financial markets as investors worry about the health of the global economy, with a slowdown in China and volatility in its markets making for a nervous start to the year.

The Shanghai Composite lost 3.5 percent, while the CSI300 tumbled 3.2 percent. That put the former on track for a 9 percent loss for the week, and the latter for a decline of 7.2 percent.