A plunge of the Turkish lira to record lows sent shivers through global markets Friday as investors started to worry about contagion, especially for the European banking sector.

The embattled Turkish lira tumbled almost 20 percent to new record lows against the dollar on Friday as strains with the United States intensified, but President Recep Tayyip Erdogan defiantly proclaimed Turkey would emerge victorious in an "economic war."

Concerns about oil supplies have eased as major producers have stepped up output, but the respite may be only temporary as tough new US sanctions on Iran approach, the IEA warned on Friday.

Britain's economy picked up speed to outpace the eurozone in the second quarter despite mounting concerns over Brexit, official data showed Friday, helped partly by sunny weather and the World Cup football tournament.

Turkey's embattled lira on Friday hit new record lows against the US dollar, losing some five percent in value as strains with the United States showed no sign of easing and fears grew over the exposure of European banks.

Three South Korean firms were caught importing coal and iron from the North last year, Seoul's customs office said Friday, in an apparent violation of UN sanctions imposed in August 2017 on the nuclear-armed state.

The Russian ruble tumbled Thursday to its lowest level against the dollar in almost two years after the United States said it was imposing fresh sanctions on Moscow over the nerve agent attack on a former spy in Britain. 

President Donald Trump on Tuesday predicted US economic growth would soon hit above five percent in a bullish speech hailing his administration's business record.

Speaking to business leaders at a lavish dinner party at his New Jersey golf course, Trump said growth "could be in the fives" by the next quarter. 

China on Wednesday posted a forecast-busting surge in exports for July, but while its surplus with the U.S. dipped slightly analysts warned that the full impact of U.S. sanctions was yet to be felt.

A global markets rally faltered Wednesday as the ongoing U.S.-China trade row eroded investor sentiment, dealers said.